That is an awesome bike. Old MTBs make fine gravel grinders and all around bikes. I use mine (an '87 stumpjumper sport) as a commuter as well. So welcome to the u brake club. They are not very good for offroad riding but they are otherwise fine brakes for most any other use.
If you are looking for a tough, reasonably lightweight 26 inch puffy tire, Schwalbe marathon supreme touring tires are excellent.
https://www.chainreactioncycles.com/...waAl5vEALw_wcB