1986 is getting to be bit old. Few things have changed since that time.

head set size changed, went from quill to threadles steerer tube+stems, to name a few.

Your bottom bracket might be in luck though. From the sound of things, it may be the races on the BB is worn out and so has the spindle. Your crank is attached to the spindle so the crank itself is probably okay.

Just make sure that when you replace the BB and the spindle make sure the width of the BB is compatible and the threading is also compatible (you have 50/50 chance on threading) and that the spindle is compatible with the crank. Spline on the spindle has changed over time as well. BB comes with a new spindle.

Send a PM to DebW, she knows a lot about bikes.

smilingcat