Well, I tried to put the 80 series rotors on the 75 series axle and even with the 80 series hub, it still won't work. Two problems that I can see that stems from the difference in the rotors. The outer and the inner (PB drum) diameters are larger for the 80 series. For the overall diameter being larger, the parking brake backing plate/dust shield it smaller, so you cannot drop the 80 series rotor in without either bending or cutting off the lip of the backing plate. Second, the center hub/drum area is also a larger diameter, which may be enough that the parking brake might not grab the rotor.
I think you'd have to swap over the backing plate and maybe parking brake bits off an 80 series axle to fit the 80 series rotors on. Too much work just to fit an 80 series rotor when you use the same caliper
Fun experiment, too bad it didn't pan out