Air it out, scrub the seats, fix the HG and drive it

3k all in for a great driver

If it runs now with the bad head gasket, you can at least evaluate what else may be bad on the car. Seats and door cards can be cleaned or replaced, even if you have to settle for torn seats.
volvolugnut

Oh well. Roll the dice and see if a head gasket will fix it. Check for head warp.
volvolugnut

To me, questions are : what's your goal ? Is this car a daily ? Does it matter with passion for this model ?
Use an Injector-Extractor Cleaner to clean doors panels, carpets and seats. As said Abscate, let the car dry a bit after that and see the result.
How many miles ?

moldy insides points to either the windshield leaking (gasket) or the sunroof. Probably the windshield gasket.
FIx the leaks, clean the interior and slap a head gasket on (timing belt / etc, pcv) and drive it.

2 huge jobs. Good luck on both!

Neil.

Yikes! Go buy a lottery ticket!

Neil