I agree that the manufacturer of the engine is the best source for that kind of information. I have done a number of new engine installations, and in my opinion the oil temperature limit as specified by the manufacturer has some margin to allow for local hot spots. The oil can handle that. If the oil temperature does not exceed the limit in the location the engine manufacturer has specified for measuring it you should be ok. I would have more concern about the exhaust system and the cylinder heads for this installation and proposed operation. Turbocharging adds a lot more heat to the engine compartment. As an example of engines I'm familiar with, there is a normally aspirated model which was turbo-superchaged by the manufacturer without a change in cooling devices (same cooling fins on the heads and same oil radiator). In order to keep this engine cool in climb, the full power, full rich fuel flow had to be increased by 25%! An airplane with that turbocharged engine I have flown a lot for tests which put similar thermal stresses as skydiving operation on it has soon shown exhaust system cracks (after about 300 h). We had no problems with the oil.