Yes, I know Barry...think he went out of the pan business a while back and Bill Highes now sells the Darp pans.
Unfortunately, Darp does not make a 20" proto pan like the Harter. There is then the issue if the hold-down bosses cast into any other brand of proto pan are in the correct location for the Regal Raider this guy wants to build. The wing is hard balsa with a spruce spar, so the hold downs can only go in one location at the center of the spar.
Here is a Regal Raider I built a while back. Engine is a nib Torpedo 29rr, 61 Series.