I didn't know the 427 had a higher deck than the 396 and 454. Is the difference in deck height because the crank centerline is lower or because the decks are higher?
If the deck is higher, as opposed to the crank being lower, that means the heads are further apart on the motors with the higher decks. Heads further apart, other things being equal, would require a wider intake manifold.
So I've been sharing some vague memories and not facts I had high confidence in. I just looked up some info on the web, but could not find clear details.
I did find bore and stroke for the parts you are using. With a 366 crank in a 454 block, I think you're building a 447 instead of 427.
Somewhere I have a big block book. I'm going to look for it and see if I can sort this out.
