Hi,

Good idea as I think it’s the minimum you should have.
Heat in the right places is your friend.

Check your plugs for tan to light gray deposits to show you some desired clean mixture burn.
I can under stand why you think a richer running engine might feel better as it softens out thin spots in a power band but overall that comes with a price in fuel and engine maintenance.

The coolant is very important for the plugs to get hot enough for the heat range that the engineering lab boys had the plugs specifically requested for the best combustions under all driving conditions that may be encountered.

Remember the engine starts out colder and warms up from there.
A range of different temperatures are encountered throughout a year.

The heater core is a backup radiator for summer or being in traffic.
It can get rid of extra heating but running it colder, especially for short runs, is never good.

For short runs you want all the residual heat to stay up longer so everything is stressed less mechanically and chemically for optimum characteristics across the board.

Thermostats absolutely have a great responsibility in many processes of manmade products.
With your project it’s to keep the engine operating in its best “compromising zone” despite the variances.
Even during the seventies a 210 degree operating zone was tried but that was also about the time fuel injection and oxygen sensors made for a necessary change.

Carburetors, that were basically leaky float tanks with a tube (Venturi) drilled with holes, definitely had compromises everywhere. It took lots of R&D to make their somewhat “simplistic” nature do as well as they did.
Between exploitation of heat and timing of the combustion cycle it’s what has kept the “ICE” game going but now is on same path as carburetors.

I still haven’t figured out what you are using.
Do you have fuel injection or not?
Either way you need heat to make it better.

Phil