Surly the old TD42 cooling cant be that bad? I've driven mine on a stinking hot day in Perth with the A/C cranking and the gauge sat in its normal spot around 1/2 way.
My GTiR pulsar only has one thermo fan due to the size of the turbo and lack of space and it doesn't overheat even on a hot day.

Maybe just due to the age of them the radiator just needs a good clean??