I built a 468, gen 4 with the following;
wiseco 9.5 forged pistons, crane 731 roller cam, full roller motor, dart alum heads, correct isky springs, 325 runners, 121 chambers, dui dist.single plane intake, holley 850 double pump,, rex aluminum exhaust manifolds. ,,,runs good, idles good, runs cool at 150 degrees, 60 psi oil pressure, 4,ooo rpm at 3/4 throttle, but no change applying full throttle. last year 21p prop turned 4700 with stock 454 mag.
Thought it was fuel pump, installed new holley electric, shows 7 psi.. At wot , fuel flow shows 23 gph,,,,,could the heads be too big for a 468 ?? yes the throttle is fully opened, ect. Same boat, same prop, 1988 265 Force. Would appreciate opinions from knowledgeable engine guys. Thanks,
Dale

Whats the full advance on the timing and @ what rpm........I ran AFR 305's on 540's

Same prop ?
What is your fuel pressure at Wide Open and top rpm ?
Also, as asked, total timing ?

36 degrees,,,full in at 2500 I believe

mid range seems good

will check fuel pressure at both tomorrow,,,,,,,,36 degrees timing

I had two 509's with the 741 cam and I thought they could use a little more cam.
You might be running out of cam, that and the heads are a little big. I am running AFR 357's on a 598 solid roller.

plug gap is .055 as dui recommended, ( I thought it was big ) ran stock wire from ignition to trip a 35 amp relay , #12 direct from the battery to the relay then #12 to the dist
Same prop, 21p bravo 3 blade
I should have consolidated the answers,,,,,sorry,,,,,,