The only parts that are 170 unique are Pushrods, Block, Crank and Rods. If you put a 225 in it you will need to reuse the oil pan and pickup tube from the 170. If you put a 67 and earlier 225 in it you can reuse the flywheel and the only other issue is you will need is a 1 inch spacer for the exhaust pipe. If you put a 68 and later engine in it you will also need a 68 and up flywheel. Most if not all slants cranks are drilled and finished and a lot of cranks even had pilot bushings installed even if they had an automatic trans installed.