250 wATER TEMP QUESTION

[NicoSlam]

I installed my old 250 in another truck that had auto meter gauges. I got it running just as it did in my truck but noticed that the temp was reaching 220 at idle and 190-195 0n the highway. It had a 195F t-stat so i replaced with a new 180F. Did not help. I also replaced antifreeze with new 50/50 mix. no change. I even purchased another temp gauge thinking it was old and inaccurate but not the issue. In my old set up I only had an idiot lamp so I dont have a reference. Timing is set at 0 @ idle so timing is not the issue. The only thing different from my truck and the new truck is the radiator. If the truck runs cool (190-200) but hot at ideal (195-225), would that be the radiator or maybe the waterpump. The pump does not leak nor makes noises and seems to push the water through properly. I need someones experience as I dont want to damage it. The sending unit is connected on the head located at drivers side front. I couldn't swap radiators because the motor went from a 69 c10 to a 64 chevy truck. thanks for any advice.