if you base this off a 9000 deck there are 3 pistons ch on them 1.540 cast and some hypers and race speed pros 1.560 and some hypers as well as some use 1550.so you should know your piston ch before you get it deck if at 9000 deck with the stock cast piston you will be in the hole 020 and get the block deck off crank and cam center or a bhj tru deck . that way the deck is on the money. the last 350 i just did was very bad the decks were so far off that that 015 they were just coming in