I was able to begin this latest round of maintenance. It looks like the water pump and thermostat are original (plastic impeller on the WP). Luckily, the inside of the engine (at least the cooling side of things) is spotless.
I decided I'd test my original thermostat and this is as far as it would open at 200 degrees:
I have no idea if that is the correct amount or not but regardless I am going to change both the thermostat and the water pump for new units from FCP Euro. I found another thread where a poster was describing the exact same issue as I'm having and the new thermostat and water pump solved his issues. I'm hoping the same goes for me.
I'll follow up next month as I have a track day scheduled for the same track and I assume it'll still be plenty hot in August.