Ok, first off thank you to everyone for all the ideas, insight, and theorycrafting. I drove it again tonight, and I don't want to call it solved, but I will call i heavily improved.
After
@Joebob 's comment on voltage I decided to actually try to find out where that one ground used to go. I had it going to the head, but there were already two grounds there so I figured it wasn't the best place. Tracing it by the length of the wire I decided it was probably meant to go on the starter mounting stud, so I put it there. Voltage didn't drastically improve, but it improved. I was running 13-14V most of the time while driving, whereas I was at 12-12.7V before. Who knows if it helped with something cooling related, but its something that needed fixing regardless.
Next, I checked a few of the coolant lines. Per recommendation of Matt at ZZP, I raised the positioning of the coolant reservoir. His theory was that it was too low and somehow backfeeding air into the system. This is at least plausible. While messing with the ground I also notice the main coolant return was getting squeezed by the fusebox a little bit. Nothing super alarming, but it was squished. So, I mounted the fusebox better and raised it a bit. It was still touching the coolant hose, but wasn't squishing it as much.
Some combination of these
improved the temperature issues. I beat the absolute piss out of it tonight and did 10-15 2nd to third gear pulls. I would say 4 of the 15 pulls it creeped up a bit in temp afterwords, but it never went over 200F. I couldn't really find a pattern to make it do it. Oh well, good enough to ride this out for the rest of the year.
In the meantime I ordered a Blackstone Labs oil analysis kit. They can tell if you have coolant in the oil, so I can check that as well just to do my due diligence.
