If everything you've said about your bike is true ... then you may want to think about parking it ... and just walking away. Cut your losses now, or sell cheap as parts bike.
On the other hand, if you're in a place where parts are available and if you have the skills/tools or ... can find someone who has the skills, you could fix most or at least some of your issues ... maybe ....
So what skills do you have?
First thing I would do:
Pull off fuel tank, flush it and clean of crud. Pull off and clean petcock filters.
Remove Carb from bike. Disassemble, install new O ring kit. Inspect all jets, especially Pilot jet which may be blocked. Perhaps just replace Pilot jet with NEW JET. Check rubber diaphragm. Blow out all passages going BOTH directions.
Next:
Set valves correctly. (you will need shims) Bike will never run right with valves out of spec or a blocked Carb. Very basic stuff.
Check fan, make sure it runs when engine is HOT. check to make sure water pump is pumping water throughout cooling system and that no passages are blocked.
Low compression is not good. Could be worn valves/valve seats or bad rings. Compression leak down test will tell the tale.
You may need to rebuild entire top end: head, valves, new rings, valve seats, guides and seals.
Loose cam chain tensioner or ? crank chains/sprockets is a major bad news thing. If bad ... once again, maybe walk away. could be too expensive to fix and would require complete bottom end tear down. Not easy.
New plug for sure, fouled plug not good ... but unless you fix all other issues ... it will just oil foul again. Replace rings, do complete top end, head re-build. If you have skills and access to parts, do all this. But no guarantee with loose and worn internal chains/drive sprockets.
Good luck!