I can’t answer if the AA bell fits a 12” clutch behind a 6.2L but I can confirm the AA NV4500 bell fits a 12” clutch fits behind a TBI 5.7L and Vortec 8.1L with no clearancing required. I don’t see why a 6.2L would be any different. I’m running the AA bell for the NV4500 in my K10 and Burb.
K10 NV4500 swap
Suburban NV4500 swap
The AA bell fit right over this 12" Centerforce with no problems
As Mr.Chevy4x4 mentioned, don't forget the pivot ball bracket as the AA bell does not have provisions for the ball.