Runing Hot, '64 Barracuda

The factory gauge doesn't work, but it just feels like it is really warm when I pop the hood after having it on the road for a few minutes. I don't know if it was a slant six car originally. I have to find the tags from my Dad to decode it. I am only thinking it is running hot by feel and smell when I park it back in the garage. I just had the carb redone and put back on and I believe that the timing was set correctly at that time. Just don't want to dump $200 on a new one if I don't really have an issue. What are the best ways to test the temp, an external infrared gun?

Thanks everyone for the help.