I have used the Russell stainless power steering hose and fittings its not as exspensive as you might think and is a smaller outer dia than a stock or hydraulic hose
As for cooling using the cooler in a rad
Trying to use something that has a temperature of
Around 200 deg += as a cooler never has made sense to me
And adding more heat into the radiator by something that potentially runs hotter than that
I dropped ten deg coolant temp climbing long hills
In my tow rig by bypassing the rad cooler and just
Running the large aftermarket trans cooler
Also the trans temp seems to take longer to rise
And cools down faster after the climb