Big horsepower 318 builds

It's hard to say exactly how much rpm a displacement will need to make a certain power level Depends a lot on VE% and Chamber shape and CR etc.., the more efficient and higher VE% will need less rpm, the opposite obviously the opposite will happen more rpm :) .

A 318 will act like a 286 cid @ 90% VE and 350 cid @ 110% VE
A 360 will act like a 324 cid @ 90% VE and 396 cid @ 110% VE
A 402 will act like a 362 cid @ 90% VE and 442 cid @ 110% VE

There can be huge overlap depending on the builds.

With the rule of thumb of 1.4 cfm per hp which there's even a lot of variable in that, a 286/318 would need 8500 rpm to make 500 hp and a 350/318 would need a 6900 rpm to do it, add the variables to the 1.4 cfm/hp rule of thumb could be 6500-9000 + rpm.