[AIR RAM]

The short stroke will help... So will keeping your RPMs below 5500....

There is a general rule of thumb that most people in the Pontiac realm seem agree on. You will be hard pressed to find anyone to recommend pushing the factory Iron blocks much over 700HP. 700HP seems to be the consensus where factory cast iron blocks split. I think its got more to do with rotational weights, RPM, detonation and bad tuning than 700HP alone, but Ive been flamed for my thoughts and I have learned to just keep them to myself. (Kind of like being a conservative in a "progressive" world)

So based on that, NO, your block is NOT over-killed for 1000HP, Its actually under-killed because its expected to exceeded all expectations of survivability past 700HP.

I'm building a 496 stroker (4.5" stroke) and intend to run 10-15 lbs of boost. I started doing my build with a 1972 455 block. I had the 3 center splayed mains, added steel front and rear mains and filled it with Hard block to the bottom of the freeze plugs. After spending some time on the forums I became convinced that my build was a ticking time bomb so I stopped talking myself into keeping the 455 block and just bit the bullet and purchased an MR1 block... (money I didn't have but could not afford not to spend)

You're not running the long stroke like I am... so that short stroke will help with survivability.

If you are hell bent on using that cast iron block, I would go as light weight as humanly possible on your Pistons, Pins & Rods and build it to do all you want it to do by 5500RPM and the tune must be right. Even then most would suggest you are still on eggshells.

Since I went with the MR1, my goals have shifted slightly. I plan to run more RPM and more boost than initially intended (because I can) Looking at 6500RPM target and 15-20lbs boost, with a Luhn Perf LS firing order cam, HP should be some place on the moon. <--- and it WILL BE a daily driver!

Good luck with your build...