I think the 500 series block is strong enough. I'm assuming that the turbo engine will probley be less than 500" with a stroke of around 4" or less. With this type off combo. and a good tuneup, no detonation, the block and ductile iron mains should be fine. If you do switch to the KB Olds, you will need the gear drive and a special pan to fit the block. Everything else the same.