Remember that the automatic transmissions used behind V6 applications had fewer clutches in the clutch packs, and therefore a lower torque limit. They may be programmed to shift at different shift-points, also.
You'll get by with a V6 trans...for awhile.
If you can find a '91--'93 5.7L TBI Caprice/Roadmaster/Brougham engine, they have flat-top pistons instead of dish, and roller cam instead of flat-tappets. I had one in my '88 K1500 for almost two decades. They're good for a very minor power improvement (not much.)
You'll get by with a V6 trans...for awhile.
If you can find a '91--'93 5.7L TBI Caprice/Roadmaster/Brougham engine, they have flat-top pistons instead of dish, and roller cam instead of flat-tappets. I had one in my '88 K1500 for almost two decades. They're good for a very minor power improvement (not much.)