My block was milled .032 and the piston is still .004 in the hole. Like I said it depends on what Pistons you use. What comp height, what stroke and length of rod, whether the block has been line bored, if the rods are new or r&r'd. You need to figure out how much you want to take off first then tell your machinist if he can get the deck perfect after cutting that much off you'll pay him but if he cuts it that much and it's not perfect you're not paying because at that point the block is a just a door stop. At $150 to cut it you don't want to pay him twice. Whatever, that deck needs to be perfect when he's done. Remember you might have to stud the block because the head bolts might be too long after the trim. Something else to consider is (I just recently went through this) they get crazy dough to trim an intake to fit. One shop quoted me $160. Another was $250. That's just to get the ports to line up. This stuff's no joke. You need to think long and hard about what you're doing and all the consequences. Do one thing and it changes everything else. You wonder why it costs $10K or more for a motor built right?