Frank: Sorry for the delay, real life keeps getting in the way. :-)
"When warm and driving the gauge is reading at the unmarked line between 175 & 250 F."
Ambient temperature about 70 F.

ambient when it "ran too cool"
That was quite a while ago, I would guess 45F, and there was insufficient heat in the car.
Since then I had set the valves, changed plugs, tightened carb and cleaned coil contacts. I had previously bypassed the dropping resistor for the coil as the
Flame Thrower coil was able to handle the extra current and the resistance of the coil
was within spec, over 3 ohms?
I have yet to check the timing at 3,500 rpm, and check the rad with a laser thermometer.
You are correct about the manifolds.
It has also been suggested to reverse blow the rad with compressed air to insure it is not blocked.
Hopefully next week will provide time to do these and report back.
DougQ