At nauseum..318 intake manifold to 340 or 360.

you can run anything from a 500cfm to 750, it's not gonna matter much. it'll probably be happiest with 600~650

intake isn't gonna matter. the factory ran mismatched heads and intakes. that being said i'd try and find an intake that *does* have the larger 340/360 ports. but again, not critical.

what is absolutely critical is your throttle linkage for a 4bbl is different from a 2bbl as is your transmission kickdown. this must be addressed, because having the kickdown incorrect or not properly operating will smoke your transmission. and having janky throttle linkage is no way to roll.

some of this can be adapted and modified with what you have, or you can pick it up fairly easily aftermarket, reproduction or here in the classifieds.