Originally Posted by TenGrainBread

That's an interesting one. U-brakes front and rear but not on the chainstays (they look like Deore or perhaps Dia Compe brakes). Fillet-brazed headtube but TIG-welded rear end. Lugged unicrown fork. Black chrome.

I would guess it's a 1987.

As to whether it's worth getting/restoring, yes these are great bikes. The High Sierra was Schwinn's top of the line mountain bike until 1985, when the Cimarron was introduced, after which it was the 2nd best until Schwinn revamped it's MTB models a few years later. Yours was most likely made by Giant of Taiwan under contract, and the build quality and weight on these is pretty good for a production MTB of this period. The one you found has some wear but would clean up well.

I have an '86 High Sierra that I use for touring and gravel riding and it's a pretty dang good bike. Mine was built from the frame so no stock parts, but the OEM parts on these were pretty much always very good. One thing to note is I think the '87 would have come with Suntour XC Sport Roller Cam brakes, so yours might have been switched out for those U-brakes at some point.