What is your block, 2bolt or 4 bolt. Check David Vizard Powertec 10 episode that discusses building the SBF 5.0 block to handle up to 1,000HP. These blocks are known for breaking at over 500HP. One thing DV tells iis a machine shop that will modify the mains for 4 bolts with registers machined in to lock the new caps in place. This is done to any make bolck. It is likely a bit expensive, but less than blowing the rotating bits out the oil pan and side of the block.
