Arthur Dalton has already tried a 79C thermostat which got his car running even cooler but it got the engine running more on th rich side. This was the thread that got me going:
Overheating Thread
I'll wait until I run into what I consider the acid test, which is a couple of hours of stop and go traffic around NYC, to pass judgement on the 83C thermostat. So far, my max observed temp has been 90C. I'm even considering getting one of the tropical duty Sachs VFC's - that would make for multiple overheating countermeasures just like JimF has done with his engine...