Richard, are you going to flow them with the 2.3 valves?

So, what you basically need, other than the high/low bolt location, is the distance, from the front of FMX case, to the block face?

I have one on a '71, 351W that I could measure. It still bolted to the engine so, my measurement might not be exact.

Could we see the sonic map?

How do you get that out of this:

"According to my records, some of the late truck engines had pressed 1.04 WP's."

That's all I said. Are not FT engines, also FE's?

I said some truck engines and I didn't even say all truck engines. It was just a statement of fact. It appears that not many knew that.

According to my records, some of the late truck engines had pressed 1.04 WP's.

With a std size rod bearing in it, add 2.439 + .975 together, devide by 2 = 1.707.

Measure between the 2 bearing holes, with calipers and add the 1.707 and that will give you the approx length. The dist should be ~4.781 for a 6.488 rod.

Did you mean the head gasket is a 8554 PT FelPro?

I ran your numbers using a standard Scat/Mahle 18cc piston (H beam rod piston) with 0.00 deck clearance and 65.5cc heads and only got 10.36 CR with the 8554 gasket. They are 12.7cc.

With your, 70° IVC, it puts you at 7.95 DCR, a bit out of the 92/93 oct gas range for your 280 cam, you could try reducing the lash to .018. That will give you a little later IVC and see if that helps any.

If you change cams, you'll need to go to at least a 284 duration on a 110 ICL. A custom cam something like a 284-6/294, 114 LSA/110 ICL with mild lobes. Howards has lobes that would fit nicely in that range.