Manifold HP

thats all fine and dandy, and yes i understand that not all street cars need 600 hp. but your question is missing a ton of information.. so its a roller cammed 318 with a 4bbl.. is it all stock in which case the manifolods should be fine for daily type of street use. or is this a built motor? 400-500 hp??? if thats the case they will choke the hell out of it..
I'm bench building a motor right now. Just trying to get ideas and pick people's brains that are smarter than me. Trying to advoid headers on an early A body. So any info is good info.