i'm running an ATT on my 93 and haven't liked it. i keep it under 2K. i'm also running a gearvendors with 4:10's. i'll be installing the turbo from the 96, hopefully soon.
Re-reading your posts do you have a cold advance on the Moose pump? The puff limiter removes it. I can not stress enough how careful you have to be with too much advance. I have torn down my engine after high EGT towing to remove a worm clamp bolt. The 6.2 pistons were fine. After advanced timing due to low compression they were all cracked and EGT wasn't over 1200. Advance lowers EGT by keeping heat in the engine.
This said does the cold advance work?
Second get injectors from the place that built the Moose pump *to match the pump*!
If you want to run lower RPM or the rich mixture of high EGT bothers you: there are different turbos out there others have now proven. @n8in8or is an example on the track with his setup. I am "old school" as the ATT was one of the first to break the GM turbo line of thinking. For towing grades that go for miles like I did it really shines. Simply forget about it below 2000 RPM. For unloaded DD use I had Buddy reprogram the trans lockup and shift points to shift sooner with load TPS%. The stall I have will allow over 2k RPM at any time I need it.
Keep these trade offs in mind as you build your truck.
A 12cm turbine hws works ok with ds4 & db2 that hasn't been hoped up, the 14 is much better all around tho if someone doesn't mind spending the money..