I'd probably pass on the Speed-Pro L2315s. A friend in Tampa built one using them and every piston was a slightly different size. They honed the block to match the piston for each hole. Then they had problems with the stock 383 rods. The big ends wouldn't stay round and went through about 60 stock rods to get eight good ones. They ended up buying some use Hale Performance (Manley) rods and rebuilt them. Those are hard to find and Manley won't make any more of them. I think I'd look at the BBC 6.585" rods and a piston with the .990" pin size, or go with a 440 rod and pistons like these.

http://www.manciniracing.com/di94bo3st2.html