i know you cant do this without drilling steam holes right?well what would happen if you did?i picked up a 400 last week but by the numbers its a 400 block and 350 heads.the guy i got it from said it ran fine .until one day it poped and started smoking badly and had a knock.i got it for free so if it is junk ohwell the crank still looks ok no majior marks.can someone enlighten me?