'75 A model 8.25 worth upgrading or leave as is?

I did one in 98, cost $700 for a posi 3.91. Oh it looked so pretty, they washed the whole axle and painted it all black. Carrier must be changed even for 2.73's

I still have it today, doing alright.

Wished I would had built a 8 3/4 and by now have two ratios to swap out for long trips.