I have the Holley Terminator X on a 406 for about 18 months and to tell you the truth, how's that saying go "If I knew then what I know now",  I would have kept my Quick Fuel 750 SS AR.
 I only use mine on the street, it's a 4 speed car with the Comp 282 cam, MSD..
Fuel injection helps with vapor lock but a return regulator close to your carb solves that problem.
MPG, don’t let them fool you 10 is about the best I get on both
Performance, I got the stealth and found out you can’t set it up like progressive linkages, so it’s either idol or all in, makes it kinda tuff with a clutch on hills.
The ads don’t tell you that it doesn’t like dual plane manifolds or cams with 110* lobe separation or more.
Both my Quick Fuel and my Terminator X Stealth were set up on dynos so that’s about equal.
I saw my engine on a engine dyno make 430 hp, 460 trq with the Quick Fuel.
So if I had to do over again I would have saved about 1200 dollars, and I know how to work on carbs but not  EFI.  So if I start having a problem  ’ll just go back to Carburetor.

I run something similar to this with the the PCV into the back of my PI intake (with basket and birds nest).  I got mine from a company called CRAP that was in a northern mid west state.   I heard the horror stories  about sucking oil and all, but mine works beautifully.  A piece of 3/8" SS tubing bent at 90* and a couple of rubber couplings plugged into the base of my carb, breather caps on my VC's, sure does clean up under the hood

Here is a site to try.  Then just run a piece of 3/8 tubing to your carb fitting.  That's what I did for a nice clean set up.  I have no problems with drawing oil into the intake or fouling plugs.

https://blockoffplates.com/products/m1003-ford-fe-engines-billet-intake-manifold-breather-plate-w-grommet-6061-usa?variant=22891884445796&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMIirLbpPmD9QIVEubjBx3MbQBKEAQYBiABEgKrgvD_BwE

Here is a Pic of my set up  Hope you can enlarge enough to see it

I don't think The cross under design make the setup any lower.  Now the 1-2 & 5-6 tubes dropping down under the control arms really hindered ground clearance.  Which is why I keep my stance up ala 60/70/s look, I clear most normal stuff cept if I bottom out my suspension.  By he way, my cross under tubes are 3 & 7, I don't know who makes them, I've had them 50 years.

Jay; I realize there are a few other ways to get around this.  But some of us have older cars that have few and far between accessories, so our engine compartments are wide open to what might look like a band aid treatment.  Hell i didn't need to cut my spark plug wires to custom length or use SS fittings, but I did. Must be all them years of being one of those picky Machinist, I guess.
Cut the general outside shape and roughed the hole on a waterjet then finished the rest on a knee mill.    I realize the FE had two sizes on their thermostat, this is the two inch one.  I've been retired so access to shop equipment is no more   I still got the drawing if you like but it would be a no brainer for you after seeing all the mind boggling things you've been up to. You've done some great work (not easy), but maybe you'd like to fill a nitch for the everyday FE guy thinking about EFI.
Just a thought

I was going to put the sniper on my FE but Thru some investigation was told that Sniper having its ECU in front doesn't like MSD distributor Fords distributor location being so close it can cause EMI (?) with the timing control Holley uses a Hall effect which is suppose to be cleaner. Also hope you don't mind not knowing your engine temp. because the EFI needs to plug into Fords one and only water bong.  They also say that EFI likes single plane intakes, but you may be able to get away with a 1" open spacer. If I'm thinking of the electric fuel pump that comes with the kit, it's pretty good, quiet to. Iirc the sniper has a built in regulator cause you need something like 50# of pressure and you'll also need a return line to your fuel tank. these thins don't just bolt on in an afternoon it takes some planning.

I'm looking at the Terminator now since it's electronics can be placed inside the cab also have an idea on the water temp hook up, but still in the works.

You can get the whole kit at Precision Oil Pumps $40 bucks
  Valve , Spring, and correct plug for the block


http://stores.precisionoilpumps.com/oil-system-components-1/