That time of year! Cooling ???'s Kinda Long

OK. Already searched, need some feedback. I do not have an aftermarket guage so please consider helping anyway!

I live in GA. Get's pretty hot here. Anyway, I was between the second mark and the half mark in the normal range and the car never seemed to go over the half mark until just recently. The new radiator was already installed when I purchased the cAr. It has 42K original miles on her. The fan clutch seems to be fine. I did over rev it into the redline twice when I missed a a few shifts but does not blow smoke and the oil is fine so I really don't think it's a head gasket.

It has been getting warmer and now idles at the halfway mark and goes up to the middle between the half mark and the next mark all within the normal operating range. It doesn't overheat whatsoever. It will come back down to the half when cruising.

My question is what do you think the increase in temp is from? Would I be better served to get a 180* thermostat and maybe a heavy duty fan clutch here in GA?

Please let me know. Going to an eletric fan or getting an aluminum rad is not an option right now. Next year when I have the heads done and some other go fast mods I will consider the cooling upgrade.

Also, I recently had gears installed. 3:73's if that makes a difference since I am operating in a higher RPM range.

Thanks. Appreciate the advice and suggestions.

Thanks.

Last night I felt the top rad hose after a drive and it was hot. the lower hose was cool. I think it might be the stat. I am going to get a guage this weekend and also go to the 180*. We'll see.