For what its worth, I would like to ask, what degree Thermostat are you running? I originally had the 195 degree thermostat, obviously hotter, so I swapped it to a 180 degree thermostat, stock for my 1970 198 slant six. I noticed a pretty decent difference in overall engine temperature looking at my temp. gauge.
I would also recommend making sure your cooling system is good to go, and your carb settings; mixture, idle speed, and all necessary filters are checked.
Heat shields, electric fan?, all recommendations on this page are perfect for your situation.
It sounds like a lot, but checking all these aspects in your car can save gas and money, and save you from aggravating hot start problems.