How much advantage in adding rear disk brakes?
How are you driving this car? Yes the fronts are a big improvement on most cars, but if a street cruiser then not much will change with rear discs.
If you guys are having trouble with rear drum brake shoe changes on a rear wheel drive car then go buy the right brake tools, or go buy a new car with a warranty.
the dual calipers on rear for drag racing are great for holding it on the starting line when you don’t have a trans brake.