Bob, it seems likely there is a blockage of some type in the fluid path.

Check a few things first.
1) Bleed screw is actually made correctly....meaning fluid can pass through completely.
2) Bleed screw threaded hole is able to pass fluid.
3) Fluid path in the new throw out bearing is open and properly made.
I say this because these things USED to be one of the normal items that was just made correctly and never gave any issue......Not so much these days.
Aftermarket new parts are riddled with stupid issues like this.

Once those items have been proven good then move on to the rest of the system that was left untouched on the truck.

Start with the fluid line....it may have collapsed internally and only gives trouble when under pressure.
I had a line like this years ago.
It looked perfect on the outside.
It allowed fluid to pass via gravity so it seemed "open".
But when pressure was applied a portion of it (inner liner) would wad up and block the fluid enough to cause issues.....OH, and it was a brand new brake line too.

There could be some junk that moved from the bottom of the master cylinder into the line as well. Thos things get a bit dirty and when we start moving things around stuff "breaks loose" and finds its way in the system somewhere else.

Finally, prove the master is still transfering fluid.

So much has changed over the last four years....I am wondering who are the current good guys building and selling complete 9" center sections?

I am doing a swap on a 65 Shelby GT350 so I want to keep the original center section intact and original.
It just seems easiest to buy a complete center section for this job...partially due to time constraints too.

I will end up with a 28 spline Detroit Locker (or Eaton Truetrac) 3.25:1 gears and a nice case and pinion carrier.

Who do you know that is providing good customer service, good products, and generally ticking the boxes for a good place to do business with.

I know I can go online and find this stuff, but I'm tired of poop head online businesses, so I'm searching for a good place.

Thanks.

200*F for oil, or water, temps is just fine...no worries.
220*F for oil, or water temps is just fine....but getting up there.
Many choose temps in the 160-180 range and that is not ideal for many reasons...too cool.
But even 235*F is okay for one of these engines.

As long as those temps are under control things are fine.
"Under control" means the temp has been reached but the temp is sustained....not creeping up, or going up, down, up, down, quickly without a peak or sustained temp the engine reaches.

60 weight oil seems excessively heavy.
This is causing a lot more stress on the oil pump driveshaft, and cam gear driving that oil pump.

If your bearing tolerances are correct (depends on parameters of build) you should be able to run a thinner oil with no issues...a 10W/30 for instance.

Switching to a synthetic oil, after break in, is not a bad idea so long as you run an oil with a useful additive package for your needs.....Most synthetics these days are already set for anti-corrosion as well as coating/sticking to metal surfaces to prevent corrosion when the engine sits. Check into the specific oil you intend to use to learn the parameters of that oil formulation.
By the way, those formulations are subject to change every 6 months so check up on that from time to time to know what is in the oil....this stinks because it is effort we should not have to deal with, but it is the realities of engine oil these days.

Concerning your temps with the oil cooler....They do seem a bit high at 230*F while using an oil cooler....Maybe your oil cooler is too small, or not working efficiently.
But then you say you have the solid block so there is less water in the block taking away heat.
Again, as long as temps are under control it sounds fine.

If you are not running a T-stat with your oil cooler I suggest you install one.
With the T-stat you have better control over the oil temps, which serves the engine better.
Set the oil cooler T-stat around 195*F (meaning it bypasses the cooler until temps reach 195*F)

Imagine your daily work as the shop oil boy and this engine is providing power to the main shaft for the whole shop.
There must be 50 oil cups on that engine, not to mention all the exposed oiling needs as it is running.

I was surprised how fast they got it turning with that 38 foot stroke....okay, maybe its not really 38 feet, but it is a long, long stroke.

Yes.
Find a place like Pirtek and have them make you a proper hose.
https://www.pirtekusa.com/

I don't know if you have this company where you live, but I bet you can find a similar type outfit.

They will make a hose for you to fit the application specific needs.
They will use hydraulic fittings and tools to build the hose to withstand the pressures.

What specific hose, and specific fittings are currently being used?
Pictures are good, and brand names and part numbers are even better.
I want to see the bare fitting, as well as the bare hose please.

There are a number of different stainless braided hose styles and fittings and some of them just won't work for this type of use.
Even if the hose is rated to a certain pressure, the fitting to hose connection may not be adequate.
Let us know what you are using to better help you find a solution.

Thanks again....I really do appreciate your input.

Great answers so far, and thank you.
The engine is in a car.
No fuel in the car for a long time...actually no gas tank at all right now.
The gas tank will be new when things get fired up again.

Unfortunately I don't remember if I fogged the engine or not....I think I did.

I plan on looking around with a bore scope prior to any crankshaft motions.
I plan on removing the valve covers to look at the valve springs...looking for and signs of rust.
I plan on priming the oil system prior to turning the crank, then running the oil primer while turning the crank and getting all valvetrain parts lubed well.

I am actually thinking about pulling the intake, then installing all the valvetrain again, then priming to see how things look, but this might be a bit excessive.

Still, a few hundred in gaskets and time is nothing compared to rebuilding an FE again.

The carb (735cfm Ford Holley) has been dry and will get a rebuild prior to the fire up.

I may even go so far as to pull the C6 to install a new seal so the trans does not leak upon startup....but I might wait to see how that goes too.

Please keep the ideas coming, and if you have any reasons for a certain thing to do please explain them so I know why I am doing instead of just doing.

Thanks again and have a great day.