Todd,
I haven't visited this thread in a while. I've been working a lot. Probably just missed it when it popped back up.
Glad to hear most of the issue with the oil pressure was just a bad gauge. Also interesting they changed the bolt length. I might have thought of that, but I haven't had an Onan apart, so I have no point of reference, lol.
On the governor, you should just be able to change the governor spring position to fix it. I'm not sure if it needs to be more or less sensitive. Too tired to think it through. I like them to be just a tad more sensitive than recommended. Makes it respond to a load quicker so you don't have too much droop. Too sensitive though and the engine will tend to overcompensate on a shock load. (Like when the plow is dropped in the ground while moving, or engaging a deck.)
Overall, awesome job. I was hoping to get to that 9 I got earlier this year, but it's probably going to end up being a winter project at this point. But hey, you've had this one waiting how long?

It's completion is sweet. For you, and us!!