You’ve got a very nice, classic rigid bike there. Honestly, it should be kept original. If you enjoy the old-school feel of 26ers, you’ll be better off getting a proper hardtail in the second-hand market that came with the right geometry for front suspension, disc brakes, etc. If you start messing around with upgrades the bike was not designed for, you’ll quickly realize that it won’t handle as well and it’ll lose its mojo. You may regret the wasted cash. Keep in mind that 26er hardtails or even full-suspension bikes from 12-20 years ago can be found at bargain prices on Craigslist or Pinkbike. Highly recommend going that route.