Man, I got all excited until I went to the CDNN website.
After looking at the picture, I think CDNNs offset pin is the same as those that came with Colt upper caliber conversion kits.
Unless I am mistaken, they will only work with large hole lower only if it is not slabside (like most of them are). The metal around the front detent pin for the take down pin is what will keep it from rotating. Otherwise the pins will be free to rotate like the aftermarket ones. Most aftermarket receivers have this feature and are small hole already.
Why Colt ever did the large hole thing is beyond me. But they did switch it back, although they are not on models I want to buy, the exception being R6551 Sporter target models with normal fire control pins.
I have the same problem with my Sporter II and small hole M4 flattop upper. Because of the rotation, sometimes the upper is tough to get open unless I use a brass punch and hammer on the rear takedown pin.