This sounds so familiar to my car. I messed around with everything, cold case radiator, flow kooler water pump, high flow 195 and 180 thermostats, more aggressive fan, and mine would still get hot idiling/sitting at stop and go lights etc. She’ll cool right back down the second I’d get moving a bit again, but as soon as I started sitting, that temp gauge would just start a climbing.
My next step was going to be to throw a good electric fan on there and see what happened, but just before I ordered it, I received some real sound advice on hooking up vacuum advance on my car and making sure to have it hooked to full manifold vacuum so that it increased the timing at idle, and wow, that cheap little $10 part did the trick. I know they make adjustable vacuum advances, but I just ordered a few different standard ones from my local parts store, and found one that activated on very little vacuum at idle and it completely cured my car. I can honestly let my car set and idle on a 90+degree day. Best and cheapest upgrade I’ve ever done to my car!!