[cobrashoch]

Todd - Yours is a good logical question that degrades to a small vs big d**k contest most times unfortuately. But to me this type of question is exactly what this forum is supposed to be about.
Most big cube motors will easly get you to the magic 500+ HP numbers. But you will need to reverse engineer out some possibilitys based on experiences of others, as I see your basic question.
For example a 385/BB is not in the cards for a ERA SC car in my opinion. And I'm sorta a 385 type guy.
With a FE and a ERA SC car, and a big cubic inch motor you can use a milder cam and compression and still get to that magic 500+ number. You can get there with higher tech. solutions too.($$$$$$)
But that 500 horse power is no guarantee that the car will run well either. Enter the REAL costs.
Oh those costs. And I'm not just talking about the costs of the engine/ tranny either. I allways tell new-be's to expect to spend about as much money on the rest of the car as you spent on the motor, to harness that power. Those type of costs are usially over and above the costs of the basic kits most times too. When you begin to think that way it then becomes a question of direction, and your plans for the car too.
Another cost effective, traditional hot rod way, to address this issue AND retain some flexibility, is to consider a centrifical supercharger. On the combo. you presently have.
Whatever your choice, remember that engine power and how your car runs are two very very different things. And that's usially why most guys upgrade to higher powered engines, and are disappointed mostly with the results.
cobrashock