If you look in the DC/MP Engine Book, for the small block windage tray they recommond providing more openings than the comes on the stock tray. So if you use one, modify it.
I use the factory ones with stock pans on the 4" engines. It takes a l;ittle tweaking to get them to fit properly and you need to run main studs for use with a tray or I don;t think it will clear. I also open the stock slots at least 25%. If you're racing the car and run wider clearances and higher rpms with an HV pump - then I'd invest in a good pan and scraper over the tray. A deep pan will get the oil down and away and the scraper will pull it off the crank better than any tray might.