ATS all the way. 3 yr 150k mile warrenty in writing. Firm shifts but not to violent. The problem with a lot of single disc converters and the VB kits is they bump up line pressure in order to hold the clutch in the converter. Necessary because the disc is usually wider than stock so more surface area = less pounds per sq inch. Stack the clutches ( 3 or more discs) and you have lots more surface area with the same psi across them.
I have driven lots of trucks with lots of different trans mods. Can't recommend ATS highly enough. And BTW. You can talk to the owner.
You will spend a lot on a converter and vb and the $$ to R and R the trans. I would buy the best, not that much more money and you won't be doing it again.