if you install a 12 bolt rear, some have 2.75'' drums... you're half way there. this along is a great stopping power.
Want to know about swapping out a rear end.
and what to use Here's food for thought.... on 50’s chevy’s By: Jim Forbes
'''''''''''There are lots of rear ends available! Some fit better than others. For 6 lug rear ends, the 64-69 1/2 ton 2wd Chevy (and some GMC) trucks have a 12 bolt rear, about 60-61" wide (I measure them where the wheels bolt on). The 70 2wd and 70-81 4wd have a 6 lug 12 bolt that is a couple inches wider, but will fit under an Advanced Design or Task Force truck as long as you don't get too wild with wheel/tire width. The heavy duty models have a 2.75’’ brake shoe, that’s stopping power. The 12 bolt truck rear ends from the 60s usually had 3.70 gears, which is a bit much for extended highway driving at 75 mph. You can swap the differential carrier and ring/pinion gears from a later TRUCK or VAN 12 bolt, the 70s trucks usually had 3.08 or 3.40 gears. ''''''''''
see also
https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Main/52074/Number/376952#Post376952
