I have a 72 ss chevelle and I just put a 496 in. I have 10lbs of vacuum at an idle. my problem is I can rev the car past 3000rpm in neutral but cannot go past it in drive. the stall speed is not engaging, but does go in reverse and first gear. I checked all the basics, it has fluids all the lines are hooked up and cables. I have a msd digial 6al system with a 6500 chip and msd distributor. the transmission worked fine before I did the swap and after the swap not so much..I have no idea what is causing the issue thanks for help..