Thanks doc. That's pretty much what I was thinking, but I searched the net a bit and couldn't find anything to verify. I'm sitting idling a lot as I'm starting to tune now and I get really nervous when the temp gets up around 200. I'm comfortable with 195, 200 I get worried, and when I see its crept up to 203 when I've looked away for a bit it scares the crap outta me! (the head, cam carriers, etc are definitely "unobtainium" - though I have seen two complete engines for sale on the other side of the pond in the past couple of years.) I wasn't sure if I was over reacting or being justifiably prudent. I guess I'll try a system flush this weekend and see if that will bring it down a little.
Prior to this conversion, I had to mix aviation fuel to keep it from detonating under high load/high RPM. I'm running it on 93 pump gas now - hoping I can tune it so I don't have to visit the local airport every few weeks. (one of the reasons I did the conversion) I'm thinking the lower octane fuel may be causing it to run a little hotter than what I'm used to?