Rumor has it that he locations of the holes are to be found in old VW workshop manuals. Not your ordinary Haynes manual but the real VW-ones that the dealerships used back in the day. When replacing body parts they didn't necessarily get the front valance or rear fender with the holes in them and had to make them themselves.
I think I can get to my oval and measure sometime later this week. But it will of course have the bumpers and support bars mounted, it would be better to measure on a valance/fender that has the hole visible to get it right. As I said, it's critical to have these holes 100% right, not much room for playing around.
For now this is the best I can do (and I know it isn't much
)