Do you have an oil temp gauge? Might be worth it to do a few laps with an eye on the gauge to see what the go is. It's a relatively stock engine, & if you put a reasonable sized
radiator, that should help draw some of the heat away,too. this might allow you to run without the cooler, giving you more room to get air to the block to cool it. Wish 3j would allow you to raise the rear of the bonnet slightly to help the engine heat escape. Wouldn't affect the body shape too much, which is what the original argument against this was.