Fwiw I have a 1uz with M112 on top, have a custom bronze/copper radiator 650w X 60d X 450h -a single 400 dia fan pulling air when needed.
It sits around a 1/3 on the gauge while moving however even idling at the lights takes it quite quickly past the 3/4 mark to just below panic stations - start any sort of forward movement and itis back into "normal" mode.
Motor has about 100k on it, 20k with the blower and has done the heat up while idling from day one - the motor it replaced had around 40 k with the blower on top (120 all up) and did not do this - have never got to the bottom of why.
I have had the motor in and out a few times due to foolishness and have never had an airlock in the cooling system.
Have driven around with blower disconnected after I left the accessories belt behind and it did the same thing.
Have replaced the water pump - no difference.
I just try not to look at the gauge while stuck in traffic now...