250 is not a big deal if you use a good oil. Typical a throttle stop .90 doorcars will but 220+- in a car on a single run. Why many have circulator pumps to use between rounds. But cooler is better to a point. Cars with a brake react better when you have some temp in the trans.

Nice little shroud you made for sure and it will at least now get the amount of the fluid in the cooler to a lower temp . Nice job