It's amazing that it could have that much metal crunched up inside it and still be rebuildable. You guys are really moving along with it...won't be long now.
What did you guys use to get the crank gear off? I had to fab a plate, couldn't get a puller in behind it. Looks like you guys are doing a great job. I've always thought Onan's looked like an old Lycoming engine out of planes. Don't rush with that Onan! And they are a 20º tdc motor, Mike is right.
You know on the old lawnboys, they have a mechanical timing advance when the engines below 1000 rpm so basically for starting the ignition timing is set at 6* BTDC and when its running above 1000 rpm its mechanically adjusts to 26* BTDC. Learned that one in my small engines course buddy :D!
Surely you have a carquest nearby? Their housebrand filters are rebranded Purolators, good stuff indeed. Or perhaps Walmart? My local walmart carries Motorcraft filters, which are rebranded purolators as well. Or, hell, perhaps you can just order purolator/wix filters straight from the company online? No filter at all is better than a FRAM. I wouldn't be surprised if that FRAM is why this engine failed in the first place. I'll PM you a study that shows why I suspect the FRAM is partly to blame