If you have the time and money to put into fixing it then go for it. Or you could part it out and likely get more out of it than you paid.

The defrost only is likely a vacuum leak (mouse probably at through a hose and probably a few wires which could be the issue with the open injector circuit) and the no heat issue could be a blend door issue, clogged heater core, or maybe a bad heater valve (if equipped is under the hood)...

Luckily there were many ZJs made and you could likely find anything you would need in a salvage yard.