I am in the middle of replacing the old 305 with a 1996-2001 GM cratemotor 350, 255hp with a roller cam and single piece rear main seal. We are removing most of the computer crap and installing an Edelbrock carb and manifold. We have checked different sources for the right distributor to use. Some say a mellonized drive must be used due to the roller cam. Others say not necessary. Anyone out there have experience with this installation? Thanks, Grant.