I've been researching this matter very extensively, but I can't see that Delawares were of any importance for a meaningful time.Deleware would be a good one to breed with. Theyer a great dual purpose breed and were once a very big part of amaerican meat production.
This is the timeline:
George Ellis of Delaware created the breed in 1940. That's great but can't see any reference how widespread they got in War Time USA and shortly after the war the Chicken of Tomorrow Contest started on 1946 which was won by Charles D. Vantress of California Vantress Hatchery with a Cornish/NH Cross and Mr. Henry Saglio of Arbor Acres was second place with White Rock, very shortly after their success they started the Sire Line(Cornish/NH) and Dame Line(White Rock) sold separately to broiler hatcheries. No mention of the "Successful" Delaware/Indian River cross was never ever even mentioned(average dual purpose by any standards) on the contest. Then by 1952 the Delaware was accepted as a breed on the APA.
So it was created in 1940 had about 1 year before America joined WWI, shortly after WWII was over The Contest of the Chicken Of Tomorrow started(and ended) so by 1950 Multi Pedigree Broiler production was very strong and on 1952 the APA Accepted them as a breed, that's a very shallow resume as a production type bird.