Update: Car runs fine, pretty good in fact (knock on wood, it's an oak cabinet I made in highschool). The temp readings were somewhat false, as it would get upto 230 real quick after startup. It was air pockets (or steam?) in the system. I'd let it get to temp, let it sit. Add coolant. repeat. Jostle the car around some, knock the bubble out. Sits right at 195 now, BUT, it wavers. it will go to about what might be 205, then back down to 195. Up, down, up down. It may do it 5 times in the span of a minute. I think there's still more air pockets in there. Heat works, so the air is out of the core. And as far as I can tell, the thermostat has stopped leaking... for now. I'm not even gonna bother with it until I get my new steel housing in from da eBay.