For sale here is a Muddler tied by the late Poul Jorgensen. Comes attached to a piece of paper with the pattern name and year tied in Poul's writing.
This fly comes from the collection of a Sullivan County sportsman who, as a kid, grew up around many of the legendary Catskill fly tiers. His uncle was also close friends with many of them.
Disclosure on all of the "original" Catskill flies here on my website: I did not see these people tie these flies, so I cannot tell you they are 100% authentic. I do, however, consider my client and his provenance to be absolutely credible. Also, Dave Catizone has inspected each fly in his collection, written up authentication letters for the framed flies (some for sale here), and told me he believes the unframed, individual flies to be authentic as well.