A junkyard head could suffer from the same problems as yours, plus any number of unknowns...

If your head is basically sound, remove it and take it to a machine shop for a full work-over; they will make short work of the stripped threads and return it to you clean and straight, with tight valves, new rubber valve hushers and correct valve clearance.

As to pulling the head it should come loose once you have the exhaust manifold unbolted, if you undo the downpipe support you should be able to pry the manifold far enough away to clear any remaining exhaust manifold studs, allowing you to pull the head out leaving the exhaust manifold and turbo in place.

Do a search as to head interchangeability, there are many posts regarding such.

I did my '87 745t headgasket a couple years ago, take your time and lots of pictures to remember later where everything goes...

Good Luck!

Shifted
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--------1993 945 GLT 74,000--------1973 Suzuki Jimny 'Brute' 61,000--------