I put Mach 1 brakes on my 90LX front and rear. I did not use the nort race car brackets but instead modified the stock brackets. I took some pics when I first started doing this, so the pics show stock SN brakes.
I took the right caliper bracket and cut it to use on the left side of the rearend, and vice-versa with the other bracket
I mounted the bracket's flat side to the backside of the rearend flange and mocked it up to see how it would fit. The spacer between the brackets is what came with the Cobra brackets I'd ordered. I may need to get one that is slightly thinner to center the rotor in the bracket
The only thing I'm thinking may be an issue is there's now two bolts holding the brake part of all this to the rearend versus 4 that it had before. But the caliper has two bolts holding it as well the main bracket. I may drill the two holes to put larger grade 8 bolts or come up with a way to tie the two halves together. Here's some more pics:
Looking at the pics again I might have been better off to cut the brackets this way instead so all four bolts would still be supporting the entire bracket:
So the the rear caliper brackets have had a section cut out of them so they can
slide over the axle tube and mount to the back of the axle flange on the other side. THen the piece that was cutout is welded back in, it only holds the bottom bolt of the dust shield , not the caliper.