The Armando pan (and assumedly the Aviaid as his is directly copied from it) requires the windage tray because the lower end of the
oil pickup bolts to the tray for stability.
As Brent said, regardless of what you do, unless you want to modify the pan you need to machine the rear main cap to get the studs or bolts recessed further down in the body of the cap or you will have clearance issues. Ask me how I know....
I run Precision Pumps' blueprinted MV-57HV. I get 25-30psi at idle and 55-60 down the road. I think you want high flow in your pump more than high pressure. Good pressure comes from proper clearances in your build.