Just posting this in case it helps anyone else: run a damn leakdown test!

So I thought I had it all dialed in and it was good to ride, I took it out to the desert for some slow riding.

Warmed it up, smoked a bit much, but revved up fine. After taking it for a quick short spin, it started to misfire--like a fouled spark plug.

Pulled the plug wonder wtf was the matter, and it was covered in black liquid. I thought there was no way in hell I jetted it rich. Had my buddy pull me back to his truck and then I noticed a similar looking black liquid all over the front of the motor coming from where the pipe mates with the exhaust flange.

Finally, I broke down and made a leakdown tester for it and ran the test. Bad oil seal. Explains why the guy I bought it from fried it and explains the oil fouled plugs and exhaust leaking. Could have saved myself a lot of banging my head against the wall (and countless 12 packs of beer.)