The plate was 865?
OOPs! Edit - I just looked again at the underside and realized I measured the lower plate with the bearing, not the upper plate with the bushing! I'll be making another pie tonight, and will quickly shut off the flame to spot the temperature of the bushing plate.
C.Bob - To be more accurate, the underside of the metal plate that goes across the inside of the grill and holds the bushing was 200F. The pizza stone was 865F.
As I thought about it overnight night, that bushing could be a bit over 200F as it receives heat conducted down the drive shaft. I'll need a bit more courage to aim that IR Gun down into the shaft with that blow torch roaring. (Ok, I'll just turn the flame down for the reading, assuming I can even hit that spot with the gun.)
In sum, this is a great science effort, but for those just wanting to know the answer: "the bushing doesn't get very hot".