8 3/4" 3rd member re-gear/rebuild

The 8 3/4" in my Duster currently has 2.94 gears and a worn-out clutch-type Sure Grip diff in a 741 case. I got a 489 case with 2.76 gears and open diff which I intend to swap over the Sure Grip unit into (after new clutches) as well as a 3.55 ring and pinion. I got the full kit, gears, and SG clutches from Dr. Diff including a crush-sleeve eliminator.

Now I'm wondering if I should attempt to fully assemble everything myself or take it to a drivetrain shop to have it done; I've done 3 ring and pinion swaps so far (one in a Ford 8.8 and two Mopar 8 1/4" units) and unless I got really lucky with the pinion depth shims it was a royal pain in the @$$ to get set up correctly. The Dr. Diff site said the ring and pinion were made by Richmond so I'm thinking I need to properly measure pinion depth which I don't have the tools for. Regardless I'll be rebuilding the SG unit, installing the pinion bearing races and ring gear onto the diff carrier myself.

Note the main reason I'm leaning to take it to a shop is the Duster will not be driveable the whole time I'm doing this as I need to remove the pumpkin that's in it now to grab the SG unit.