Ok, I'm new to the 4spd setup and swapping from TH350 to SM465. How can I tell if I have the correct flywheel. Are Chevy flywheels internally and externally balanced or just uniform for the Sm-465? What is the minimum thickness before trashing one? Currently I have a 350 but will be stroking it to 383 with an internally balanced Scat crank with the 350 mains, will any changes need to be made in the flywheel at that point?