Forget the Saginaw. That was a cheap four speed for low hp small blocks like my 71 Chevelle. Forget about the tall block, too. Those was for medium duty trucks that I think used taller pistons for durability, not more power. I like the 427 just because it is internally balanced and has less rotating mass as long as the price is right. Pontiac engine builders use 400's over 455's for the same reason. Have a blast.