check around local auto parts places, they're commonly used by repair shops now .... failing that, don't let anyone catch you putting the candy or meat thermometer from the kitchen in the rad

with a 185 stat, the engine should be running 185, the 235's usually run cool, so the stat forces it up to it's temp, can't imagine one running much over stat rating - good idea to check new stats to be sure, not unusual to find defective ones - also make sure you don't have an air lock, fixed by drilling a small hole in the surround next to the opening bellows
Bill