[Clifford Pope]

I would advise fitting a new temp sender, just so you know for starters that the reading on the guauge is correct. I found that although mine appeared to work, it was overstating the temperature by about 1/8 full scale - 2 needles'thickness.
I also found a new radiator did cool better (too much in my case!) even than a fully removed and flushed out one, with the dead flies blasted out. I think the fins must corrode or bend or just lose their radiating properties somehow.