The power steering issue is from the actual pump itself.
Idealy you want to underdrive the pulley.
The pump actually starts to re-circulate oil back to the resovoir after roughly 750rpm. Due to your engine now roughly running on average around 6-7-8000 rpm the amount of fluid that is returning to the overflow is high, causing alot of friction through the pump, thus causing it to over heat.
A cooler will help the solution, but under driving the pulley is a must.
also, incase it sounds weird, the pump is at 100% duty cycle at 750rpm to make it easy to idle into a car park.
research the V8 brute utes, they where exploding pumps from excess heat due to their average RPM.
I have underdriven the one on my car, added a cooler and I dont have this issue any more.