No end play

Does it matter if pump is installed with trans laying parallel or does it need to be straight up and down on its end??

I just assembled a 727 over the weekend. I stood it up on end and strapped it to a leg of my workbench to install the clutch assemblies and pump. It made it much easier to align the clutches and ensure everything was installed correctly. Plus, it made it a little easier to measure and verify end play.