Initially, my thought was that this Kessler transition model discovery verified what the Blue Book of Airguns had, but, my mistake, this model is not described at all in the Blue Book. Instead, the Blue Book says that there is a two-piece model that looks exactly like a Rochester but is marked as Kessler. Such a gun is not pictured and nobody has ever come up with an example and, as we can now see, the Rochester/Kessler transition model is in fact an entirely different animal. It's a combination of Rochester and Kessler parts and, at least from the one example we've seen, is marked Rochester.
The confirmation of this Rochester/Kessler transition model by documentation and by example makes the prospect of finding a legit Rochester marked Kessler at about zero. It doesn't make very much sense that Kessler would have had to use Rochester marked barrels on their new design and at the same time put together full-blown Rochester models using Kessler-marked barrels.