I don't doubt for a second that you have a coolling problem as it's creeping up and not stopping- I'm not sure why anyone is telling you 200/205 is ok when it's still climbing. sounds like 200/205 just happens to be the point where you have had enough and stop the madness, not a steady running temp for long periods.

However, it's probably worth looking into if your gauge is correct. Clearly it's accurate enough to tell you that a cooling issue exists but as you embark on the journey of thermostats/fans, etc, it's worth having an accurate reading as you will be comparing engine temps to thermostat open temps vs. size of fans and rads. The temp data point should be as accurate as possible.

the factory gauge in my 68 charger decided to be 30 degrees off after sitting for a loooonnngggg time. A gauge I calibrated many moons ago and I know it was correct back then as 230 and climbing triggered my car's gag reflex and she'd spew all over the ground. Old mechanical gauges, old wiring, old mechanical 5v limiter- old cars, man


I've been down this road with a mild big block in my charger. I believe I have finally solved it with high flow 160 thermostat, a very large fluidyne radiator, opened up core support, dual 1300cfm spal fans, flow kooler waterpump. I'm running a sniper efi that controls the fans individually. It will idle at rock steady 168-170 on just one fan with mid 50s ambient. the proof will be in the pudding soon enough.

many years ago before I ran this setup I ran a be cool direct fit which seemed like a joke to me. this was before the web was a good resource and I picked it out of the summitt catalog. very small rad. best results I ever had with that was no clutch, ghetto flex fan, and a cobbled together shroud.