I currently have a fresh 350 in my 71, had the motor balanced with the flexplate. I am planning a conversion. Is this true: I read that if you put the manual flywheel on, you will screw up the balance and kill the botton end with vibration?? Any truth, because if that's the case, it'll scare the hell out of me.?? Also, everone says the saginaw is crap. will break. Will a saginaw hold up to my 350 w/ 3.08 gears??