Is it possible to weld a different balance weight onto a flexplate (such as a 1987 5.0 balance weight onto a 1972 c4 flexplate)? I was thinking that one of the guys from work could do it for me if it would work. I would like to put an 87 5.0 into my 72 Grabber since the motor is acting like it's just going to puke, and I can get a great deal on a 350 horse motor.
I don't think you should entertain doing that. Balance is somewhat critical. Get the correct conversion flywheel and be sure of no problem.
