I enjoyed reading your post, but I wonder if your ICE rebuilding skills extend to EVs in general, and Teslas in particular?
When you add up the cost of both cars, and expected time spent putting things back to operating condition, what will be the total you’ve invested? For that amount are you confident that you’ll have a safe vehicle free of continuing problems? Would you feel confident in the car’s reliability and safety?
Only you can answer these questions, but years ago I remember a friend who tried a similar experiment with a well worn Ferrari that had lots of issues. He’s a skilled mechanic and thought all would turn out well. It didn’t and he wound up going to a Ferrari expert to get everything sorted. The mechanic told him the famous line: “There’s nothing more expensive than a cheap Ferrari”.
I’m not saying this will happen to you, but before you jump in with both feet maybe checking with Tesla would be worth the expense and time. Ferrari has proprietary diagnostic computers that are highly specialized to sort out problems. My guess is that Tesla does as well. Compare that cost to trying things on your own, and possibly finding out that some of the work you did won’t solve the problem.
Best of luck - You’re a braver man than I!