I tighten up the back lash on my old A/SA NHRA stocker, 1963 Plymouth 415 HP 426 M.W., it had 4.56 in the stock 742 case with the clutch type Dana posi like yours, that help make it quieter on the down hill return road in neutral I didn't try looking at the pattern, it had over .012 back lash with grease on both the ring gear and pinon gear.
I have and do set up my own new gear sets in 8 3/4 and Dana 60 using a pinion depth tool for the pinion depth, not using just the pattern only
I've been told many times over the years by race shops and other who do a lot of gear setting up to always go to the minimum back lash on both 8 3/4 and Dana 60 with new gears, street and strip or drag race only I do that now
On your deal I would set the back lash to the minimum now and relook at the pattern to see if that helps make you feel better or not