TA 340 6 pack in a 68 Dodge Dart vert

Let me re-phrase that;
If you suspect it is running hot,then, put an aftermarket gauge on it.

I can't recommend a gauge Cuz I'm running an electronic, home-made IVR; and the gauge climbs to it's designated position and never since 2000 has is it deviated. So I assume it's working, but IDK that for sure. But I trust my cooling system......... and the 7 psi cap.
See when you have a 15 pound cap, the temp can skyrocket before it blows the pressure relief, and maybe you notice the steam coming out from under the hood...... and maybe you don't. But by then,the engine is already borderline overheated.
IMO the 7 pounder, will blow early, and thus give me plenty of warning........ But that is not my primary reason for running a 7. The low pressure reduces the stress on the entire system, and nothing has yet broken, ruptured, or worn out,since 1999. The 26" A/C rad, in my combo, is easily able to handle the heat, augmented by the aluminum heads radiating copious amounts of heat. The 7 blade steel fan, on the Ford pick-up Thermostatic fan clutch, is, from time to time, reminding me that I do in fact have a cooling system.I run it at 205*F

I have a little Autogauge 8000rpm,270* sweep tach, that I purchased new in 2000. So;Since it seems to be surviving ,I suppose I would recommend their products.