Those temps and pressure don't sound horrific, under the conditions...

That said, before you add a larger oil cooler, make sure the cooler you're using is free and clear and getting fresh air! Often coolers just end up stuck in front of the radiator, and work more like an interheater than a cooler!

On my ITB car, where cool oil (as is, not more than 230 peak) is a necessity for longevity, we eventually went with the 8.5x11" trans cooler for oil. Works wonders, and with a stock water rad we don't have cooling issues any more. Ever. Even when pushing 100deg ambient.