Any old bike parked next to a bunch of really cool vintage stereo gear is a classic as far as I'm concerned.

Overhaul it, get rid of that fugly stem, buy some new tires, and ride the heck out of it.

One thing I've found with old MTBs is that if they haven't been ridden off road (and most of them have never seen single track), the parts tend to be in decent shape. They're tough bikes that make excellent commuters, tourers, and gravel grinders. Plus they're fun to ride.

I love old MTBs so yeah it's a classic even without the stereo gear in the background.