The windage tray keeps the crank from picking up excess
oil while it is spinning, thus making more power. The scrapper mounts on the side rail and clears
oil off the crank, thus making more power. I use a windage tray but no scrapper, and also have 5 trap doors to keep the
oil in the sump. Depending on the driving you're going to do..I'd be more interested in the trap doors, then next a pan with a windage tray built in....MHO
After looking at your link, that seems like a good pan.