Depends on how much stall your running/going to be running.
Ive got a LT 72 P trim,.63 ar and I am running an AOD with a 3200-3400 stall with t'brake from CK. Havent put new engine/tranny in car yet though.
If you were using the same stall it would spool a little slower and it would kill some low end, my car would pick up 2-3 mph on a 70 p-trim from the .63 to the .85 but since you changed the stall you should be fine.