You might as well go ahead and upgrade to an 8.8. And yes, you can use the 94-98 rear, but it's a little more involved due to the disc brake setup. Also, you may have some tire clearance issues. I believe those rears are slightly wider and your wheel offset can be a problem. Do some reading on it, since it's been a while. Seems like the rear end itself is the same width as fox mustang, but the disc setup is what makes the assembly wider. Either way, there's a possibility you might have problems depending on your wheel choice. You'll also need some e-brake csbles, iirc. Not sure if you can use the cables from the donor car. If you're wanting to stay with rear drum for cost and simplicity, just find a fox mustang 8.8 rear and then get a set of 5-lug axles (around $250 shipped). I believe those would be hardened axles, too... so an upgrade, as far as strength is concerned.
As for the front, cheapest anand easiest is to purchase 5 lug swap rotors. The problem is that not all wheels will fit due to the size of the hub, I believe. Best bet is to use 94-95 spindles and rotors. That will accommodate any 5-lug mustang wheel, I think, oem or aftermarket, as long as your backspacing is correct. The problem with just doing the 5-lug discs is that the center caps won't fit some wheels because the hub sticks out. I think you can use wheel spacers, but most people aren't a fan of going that route. 96 and later spindles aren't a good option, either. I think there's something about control arm length, alignment issues, ball joint location... heck, my memory isn't what it used to be lol! I decided against 5-lug swaps because I have 5 foxes and like the idea of being able to swap wheels/tires around. I may swap one of them some day, though.