Auto, which one?

[vroom]

I am in the process of collecting parts for my 69 build, which includes converting to diesel & auto. At this stage budget limits to 6.2/6.5 as the duramax is to much from what I have found so far.
All the 6.2/6.5 I have found all come with no trans, so question is what works with them?
At the moment I have found 3 options, 700R4 (lots of $$$) a 4L60E Automatic Overdrive Transmission and a 6.0 vortec max trans with a marking 6csd?

What's suitable, any computer issues, will also have to be colum change and I haven't found any new colums with any other options other than 3 or 4 speed.

Thanks guy's any advice will be much appreciated.