I stroked my 383 to 434. I originally got a kit from muscle motors. I highly recommend getting a kit from somewhere else. I had to get 3 crankshafts from them before i got one that was acceptable. They also sent me the wrong pistons. I ended up going with a crank from 440 source. I recommend them. The crankshaft was perfect. If you have any other questions fire away. I had no other problems with my build other then the crappy crankshafts.