M500 Insulation Tester/Electronic Megohmmeter – 0 to 1000 Megohms, 500V, with Soft Carrying Case

The engine is done, there might be some salvageable parts inside. But with how much damage there is here, a replacement engine will be cheaper than replacing the broken parts. The alternator is probably fine, so long as it spins freely. Look at getting an inexpensive megger (or see if you can borrow one), that will allow you to test the windings. I would look for a used engine for it. Edited to add: Here is a megger that should work for you: https://a.co/d/0fbHt9iF