i have a 71 malibu 350sb which i believe is 2 bolt, Im eventually going to build a 383( around 450 horse or more) hopefully. would my 2 bolt be able to handle this amount of horsepower or would i need to find another 4 bolt block? thanks

Replace the bolts with studs, and it will hold over 500 I believe. Kirk

If the engine is balanced well and studs are used for the mains, then you should be fine at 500hp or so. This is what I was told anyway. I know guys putting out around 400hp or so on a 2 bolt (with nitrous) and their engines are holding up just fine. I know 400hp isn't 500hp though.

You can achieve some really good 1/4 miles times with a 400hp engine. It's all about the gearing and hook up.

I'm not sure if its RPMs that can cause it to fail, or the HP. I've got a smidge over 500HP on my 2-bolt 400, but I keep the RPMs under 6000. Only time will tell how long it lasts.