Suggestion Kev; Why don't you PM Jay on FordFE telling him your proposed build specs and ask him, in his opinion, what the best carb/intake combo would be best for your application?
"Others" got the impression that I was diss'n Jay and his credibility, couldn't be further form the truth. I highly respect the man and his FE knowledge.
FWIW, the engine he used to make that round of tests on was a stock stroke with stock, non-CJ iron run-o-the-mill heads and a v-e-r-y mild performance cam. You're going to be running a nominal 20% more displacement (527 vs 428). Your heads will flow at least 50% more then the ones used in the tests and your mechanical roller will be monstrous compared to his smallish cam. Your combo will tremendously outflow his setup. The intake that was "perfecto" for his motor could quite possibly cause yours to fall flat on it's face, or close to it by 4500 RPMs. Your setup will be much closer to one of Jay's mustang race motors, no Dominator, maybe a bit less compression, less lift and duration on the cam, but very similar.
Most of the FE masses (including myself) will never have a motor like yours. They may comment and say their iron head 390 ran good with this 'n that or this widget made the most horsepower for me ... but... that really holds little value to you ... and quite possibly could be vey BAD advice in your case.
Jus' a little "friend"ly advice, my friend
We be cool... just be careful who you listen to.
