I just picked up a 74 Nova for $500.00. It has a stock 350 with headers and a turbo 350 tranny. The flex plate was cracked so I put in a heavy duty one. Now my friend said I should put in a B&M shift kit. I don't know that much about cars so I was wondering how will this affect the life of my tranny and will there be a great improvment in how it shifts?