The Cleveland heads make a lot of power. Even the old 4V style heads can be ported to really cut the mustard.
If you chose to go with the old iron stuff, you can make a 4V head flow about 310-320cfm. Then you have a choice of 4V intakes: the Holley Strip Dominator, the Edelbrock Torker, or you can even adapt one of the new CHI intakes. The 3V intake has a port dimension that you can easily fit inside of a 4V port.
If you go new aluminum, the CHI 3V heads will absolutely make the power. AFD also makes some very nice aluminum heads for the Cleveland. Both of these companies are Aussie companies.
You also have a choice between the various Yates heads. Most of those have really big port volumes, so it's not good for a small cubic inch engine...plus the chambers are really small, so static compression ratios would be high.
There are various intakes available for each scenario.
If a budget wasn't a factor, a 351W based Dart block with a large stroke rotating assembly (445-460 cubic inches) with a set of CHI 3V heads, a single plane CHI intake, and a mild street roller cam would be close to or slightly above 700hp.
