Not much. That block isn't exactly all that great. The 87+ block is far stronger and it's limited to around 400-500HP before you start running on borrowed time.
Turbo is the way to go. Its not the boost that breaks the block, its the power. If your running a 76mm at 6 psi or a 70mm at 12 psi. Alot of it is in the tune anyways, run it alittle on the rich side and keep the timing reasonable you'll be fine. Try to get all you can out of it...