230 - 235 is normal in the summer but 250 is a little high. I would check the air/fuel ratio and see if it is a little on the lean side. Most of the temp from oil is from the spray on the inside rotor faces so combustion temp is a big factor.

I always pick up my temps at the filter to see what the motor is being fed, but you should be close. Shoot the coolers with a heat gun to see what temp they have when it is hot. I would want to see that both coolers are getting the same circulation and not bypassing.

Are the coolers sealed to the nose opening?