I'm just guessing, but that generator head MAY be a ST-type? Under the cover, does it have brushes? If so, you'll be able to find ST-type wiring diagrams around.
Now, as to the oil filter, I have skinned that cat. I use a toilet-paper filter on mine, and it works FINE, despite what some young bucks believe. The matter of plumbing CAN be onerous, but if you can bend some copper tubing, and figure out a couple compression fittings, you can plumb it into the left-hand lifter locator bolt. If you've got a lathe, it's easy. If you've got a friend with a lathe, it's easy. If you don't have a friend with a lathe, then you need more friends.
Mind you, this entire idea came from 38AC. The work, I did myself. The brains, he did. And he's used a plethora of these.
Just PM me, and I'll send you some pictures.
https://www.toiletpaperoilfilter.com/thetoiletpaperoilfiltercompany.html