Starting turbo!

Ditto on the tuning. Aside from that, I'd say you could probably get about 400 (that really depends on the tune and piston strength) on the stock shortblock. If you upgraded to forged pistons, you could make about 500 before the rods would leave the block I imagine. How much boost are you planning on running? I wouldn't put more then about 7psi on it with those pistons...