The gauge on my 64 Dart is hitting about 80% with out ever over heating, should I be worried?

I wouldn't be too worried. it's probably just an issue with the thermostat. that would be the very first thing i would replace as that is going to be the cheapest part involved.

49 year old car? should I be worried? aaaah NO! ,maybe if your driving more than 10 mile from home on a hot day. try to record the true temp with a thermometer gun. the system may need flushed mostly the old rad core !

Thank you all for the feed back. I will have the thermostat checked to ensure it is a 180 and not a 195. I have had the radiator flushed as well. As I aid it has not actually over heated, it just vexes me when the temp gauge get that high.

One thing to consider: What you refer to as a temperature gauge isn't actually a gauge at all - it's an indicator. A gauge will give you measurements - indicators give you an idea.

After this any years, the sending unit may be due for replacement, too. Also, check the timing, make sure it is set to spec and that the mechanical advance is working correctly. Also, check the carburetor. If it is too lean, the engine will run hot.