I've been running a '73 360 block .030 over for about 3 years now with nitrous pushing around 440 wheel horsepower. She's got about 100 passes on this setup and she's about 340 wheel horsepower in naturally aspirated trim. No signs of anything bad coming from the block from a strength stand-point. I'm running a stock cast crank and untouched edelbrock LA heads too though I did put in all ARP fasteners in the bottom end, including ARP Pro-Waveloc rod bolts, main studs, etc. Good luck!