Guero, when I burp the system, I use a turkey thermometer in the radiator neck to monitor temps. At close to 195*, you'll start to see the water move across the radiator.
If you do this, please be real careful because HOT COOLANT CAN SPLASH OUT OF THE RADIATOR AND BURN YOU! It's not a bad idea to put a rag around the radiator neck to catch hot coolant that tries to splash out.
If your new t-stat doesnt have a jiggle valve, it can take awhile for air to purge. I would have used a 180* Mr Gasket stat.
I think I shared the same thoughts on another thread that other here have - that radiator isnt helping. But I DONT think that's the only issue here - you're getting too hot too fast, it seems.
Good luck.