You would indeed. I'd jump out and pop the cap right after a hot shut down, just to be see what happens and confirm or deny that clogged evap could be a problem.

What clued me in (I have a 73, different system with a charcoal canister and a vent line from the tank that I don't *believe* your car would have) is that the cap started venting. Troubleshooting led me to the liquid/vapor separator shuttle valve being gummed up. An overnight dip in a one gallon carb cleaner can took care of it.

Another trick I have used for vapor lock successfully on cars without the charcoal canister setup and no 1/4" tank return line is to plumb in one of those three legged fuel filters (goodmark sells a factory repro that can be had on rock auto for a little less impact on the wallet and has a tab that can go under a fuel pump or other convenient accessory bolt) and run a 1/4" rubber fuel line back to the tank. You can put a hole close to the fuel outlet on the sender, install a fitting and connect the new return line there. Make sure the fitting goes far enough inside the tank, preferably with a 90* bend) so that any liquid fuel in the return doesn't just dribble down the inside of the sender plate/tank. Or, put in a sending unit with a return but getting a properly functioning fuel gauge with aftermarket senders is hit or miss in my experience.

This won't help fuel boiling in the bowls though. A 1/2" wooden or phenolic spacer (open or 4 hole depending on your combo) will help with that. I've been tempted to run a carb heat shield as well, but squaring away the evap system and my coated quick fuel carb cured my problem with the same symptoms. With hotter weather coming on, I'll try an insulating gasket or spacer if I have a problem.

Knowing what type of evap system your car is equipped with, which carb you are running, how close to stock your engine is and if you have a return line of any sort will help the brain trust focus its advice.