Thanks to everyone who has posted suggestions and tips! Just a quick update. Removed the timing cover. Was actually quite easy, took about 45 minutes. I work at a machine/fabrication shop, so I got one of our experienced guys to have a go at removing the broken thermostat housing bolt. He got it out, and put in a helicoil. Looks like it hasn't even been tampered with. Will begin reinstalling it the next day or two.