Totally rebuilt my 47 engine, only to find out the block is cracked..........

Purchased a 50 engine, which is kind of killing me putting a 50 in a 47, but the deal was too good to pass up. My question is this Im debating on weather to bore it .030 OS, or not? Thats what I did to the 47 block. Had this block checked for cracks, and none found! Do I go ahead with the rebore, or just get new rings????????????????
opinions are ALWAYS appreciated.