I have a 396 SS/RS convertible (born with a 327) and I am trying to bring the rest of the equipment up to status. The radiator needs to be enlarged (21" to 23"). The tic, toc, tac should redline at 5500 (currently 5000) and the rearend need to be changed out to a 12 bolt (currently 10 bolt). I have a 350 turbo automatic but should be a turbo 400 automatic to be 396 corrrect. I've considered changing out to a four speed manual (? 6 speed). Your thoughts?