The sandwich adapter (oil feed) has a bimetal thermostat in it. This opens and closes to divert oil to the cooler for the exact purpose of keeping it at the ideal temperature. That's the whole point.
But get a "heavy duty" cooler, like for a performance SBC. There is no loss of pressure. And run all the oil through it, not just for the turbo. Keeping all the oil at the right temperature will help cool the entire motor.
BTW, it's supposed to go through the filter after the cooler.
Finally, the high volume mod only helps at lower RPMs, where you don't need it. At higher RPMs, the pressure relief limits volume along with pressure.
And according to engine rebuilders (not my personal knowledge), you should avoid the high pressure 60 lb spring, as that will wear the front camshaft bearing and distributor drive; stick with the stock pressure 40 lb spring.