Are you sure it's an 83? Mombat doesn't show the High Sierra starting until 1984. You can compare the specs/paint colors here:

http://mombat.org/Schwinn_Specs.htm

Looks like the 84 has a 5 speed rear hub, which may use a different spacing than 6/7 speed (which I think were the same for mtbs?). Just something to keep in mind in case you want to upgrade. The wheelsets on a lot of these early mtbs (even higher end ones) were nutted instead of quick release, so you may want to swap those out if you're actually doing touring with it.