4L60E or TH400

[70K10Hunter]

figured I'd throw this out in the mix see what kind of response, I bought a complete donor vehicle for my build (70 K10) the donor vehicle is a 97 2Dr Tahoe 4x4, it's got a good running vortec 5.7 but the trans is shot it doesn't move an inch either direction. my 70 truck came with a working TH400, so I either have to rebuild the 4L60E or go through the 400 to make sure it is solid.There are so many different upgrade components for the 4l60 that I could potentially spend well over a grand just in parts,this truck isn't going to be my daily driver, so other than the final gear ratio and an another gear on the top end what are the pros and cons of both ? which is more durable/reliable?
I am already going to use the vortec just dont know that I want a computer controled trans.