One question is at what percent power are these temps.  Clearly they are on the high side.   

It was full throttle, about 6000 rpm.

I’d say WOT and 6000 is not a good time to start leaning - unless you’re over 8,000 ft.  At those conditions I had peak close to 1750, so with a bit higher compression, 1800 is maybe not so far out-of-line.  Try cruising at about 5000 – 5200 RPM and a few thousand ft; then lean out to about 100 lean of peak, and see what your temps and fuel flow are.

I did just briefly, but not understanding the 1800+ readings, I didn't want to mess with the mixture much until I knew more about what I was looking at.   

Good thinking.  1800+ for very long is very unhealthy for SS exhaust.

Al