I agree with Stanton - the smaller hole at the spray gives the best effect, and the overall delivery rate should be controlled by a restrictor in the feed line to the cover: highest pressure in the small lines.
However: long history in motorcycle engines says that even an .020" hole will eventually clog with debris, shredded gasket, dust, etc. The hole must be larger if you never service/inspect it, like .030". A filter in the big line may cure this and allow smaller holes, but it's got to be pretty fine to help.
I have a feeling that the hole edge should remain sharp to disrupt the flow (rather than radiused or counter-bored).