Choosing a Transmission

[Braker68]

Hello fellow forum members, I had a very important question for you all. Which transmission should I choose to put in my daily driver '68 Chevy C10? A little background info about the truck powertrain, 2014 6.2L Silverado Aluminum block engine (with about 30 miles), and a positive diff with disk brakes (still don't know the gear ratio of the diff). I was thinking putting a 4L80E or a 4L60E auto trans. Or put a t56 (6 speed) manual transmission. If you all don't agree or have a better trans to go with the setup I am going with, then please tell me.