What Trans to use?

So I'm new to the restoration idea and am currently deployed in iraq right now for my 3rd deployment. I have a 1968 chevelle malibu sitting with a 350 and a saginaw 4 speed trans. I want to put a 454 in there but im unsure what transmission I should put in. The car to no prevail (me being the youngster at heart i am) will be beaten at times at the track but will definitely be getting very well taken care of once i get it up and shining. So i guess the question at hand is whats a good transmission that can handle the 454 and also take a little beat of beating? Thanks!