The goal is just the ultimate fast winding cruiser. This car will never see track use

Small changes to make it a better "B-road" cruiser.
We only get to around 32°C in summer, but the humidity is high. Like 80% on sunny days

which makes everything run hotter. I have an external oil cooler kit with the 9-row Setrab core (not installed), and I've thought about putting it in the stock oil heat exchanger coolant return loop. That will dump the heat absorbed from the oil to atmosphere before it returns to the radiator. Seems like a low-risk win-win.
No serious points of failure added (like an external oil cooler does).
No over-cooling of the oil.
Taking the oil cooling burden out of the main cooling system.
Using -10 lines will add another liter of coolant to the system.