Are you saying, your going to try to do a disc brake conversion on the 1st gen housing, using the parts off the 2nd gen housing?
You can simply re-use your existing E-brake cables if so. They are the same on 1st & 2nd gens. If you have to have them, then just take what you need from another donor, or buy new. There is 3 cables from front to back, just get the ones you need.
If you just wait it out, until you can locate both deeper geared diffs, then just swap them out whole, I think this would be a better option.
Or... Re-gear the rear 2nd gen now, and use the ratio that suits you best, then gear the front when you can. As long as you never put it into 4wd, until then, your fine. Can even remove the front driveshaft, for those CRS moments.