My lower is an E Series in the 1800’s. After fooling with it a bit more this evening, I tried to swap the lower from my Stag arms rifle and it mated to the DD upper perfectly. And the Stag upper mated to the Noveske lower perfectly. I’m still debating on shaving the area around the pivot pin. I may call Noveske and see what they suggest from their experience tomorrow.
Update: After applying pressure on the pivot pin while moving the upper back and forth on the axis of the pivot, it finally slide half way through. Then after working it a bit more and a light tap, it is fully mated. I appreciate the support of everyone that contributed.