I really, really, really want to put a turbo on my old sixer, as well. I am thinking a blow through set up would be best, but that is just my opinion. Icing of the venturi is a bit of an issue with the draw through set up. A blow through does take a little more fab but it is not that difficult. How much boost are you planning to run? How much more torque are you looking to get out of that old tractor motor?
Mitch