8 3/4" sure-grip swap and rebuild questions

I know this stuff has been covered before but the other threads I found didn't exactly answer my specific questions. I bought a 3.55:1 ring and pinion from Dr. Diff along with a clutch kit for my Dana Powr-Lok diff. My Duster has been running a 1967 741-case with sure-grip and 2.94 gears. I got a 489 case from my cousin when he scrapped his '72 Polara. Plan is to rebuild the sure-grip and swap it into the 489 case with the 3.55:1 gears, I will then take the open diff from the 489 case and swap that back into the 741 case with the 2.94 gears so I ultimately have 2 center sections (one 2.94 open, the other 3.55 SG).

So far I've rebuilt the sure-grip unit with the new clutches. I didn't put straight friction additive during assembly though as I wanted to save as much as possible to put into the housing after final assembly; I poured about a tablespoon of additive into a small tupperware and then poured in about 3-4 tablespoons of gear oil and mixed it around. I coated all the clutch plates with this mixture during assembly. I then torqued the LHT diff bolts to 45 lb-ft which I heard mentioned in a YT video (hell of a time finding that torque spec), tricky because I don't have a fixture (might have been a bit closer to 48-50 lb-ft as I was using a beam-type torque wrench) and I just clamped an edge of the ring gear flange into a vise with some old bed sheet material to keep it from getting marred. Is it a big deal if the bolt torque is a little over? Also just saw another thread where someone said to torque them to 40 lb-ft... which is it? The bolts were still oily and I didn't put any thread locker on them.

Next questions, do I need a fixture to torque the ring gear bolts? And is putting thread locker on those crucial? Saw some posts claiming yes vs no so not sure how important it is. I have a vise at home but haven't yet mounted it in my garage and I have doubts about the jaws being wide and deep enough to clamp on the diff carrier to hold it in place while I torque the ring gear bolts.

Also the 489 case is getting new pinion bearings but the carrier bearings on the sure-grip seem to be in great shape. I know the "right way" is to replace the carrier bearings too but is it that big of a deal? I did make sure to keep the races with their respective cones and not mix them up.

Lastly, is that special spanner tool for adjusting carrier backlash necessary? I figured I could just rig something up or carefully tap the adjusters with a driver of some sort to turn them and adjust the carrier bearings. But thinking about it more I imagine the bearings need some sort of preload once the correct backlash is set?

Was really hoping to get this all mostly done this coming weekend but that won't be the "case" (tee hee) if I need to order that spanner tool.

EDIT: I do have a FSM for my Duster but it's 1970 model year and covers the cone-type sure-grip not the clutch-type like I have...