The main benefit to z ray cross member is the tie in into the LCAThe Unisteer rack mount replaces the crossmember and bolts in using the crossmembers bolts. It's more than capable of replacing the cross member since it''s made from thick steel plate. The down side is that it's much heavier than the OEM or Z Ray cross member.
According to KRC's website, they have a specified RPM that their pumps can run, but exceeding the limit will only eat HP and not provide any additional fluid pumping. 7500 RPM shouldn't be a problem.
To calculate pump RPM use the following formula.
Divide the crank pulley diameter (cp) by the power steering pump pulley diameter (psp), then multiply that answer by maximum engine RPM.
Ex. 4.5"cp ÷ 6.0"psp = 0.75 x 7,200 = 5,400 RPM Pump Speed