I did this same thing to my 111F.
Since I was throwing the old tube away, I just stuck a file into the tube, it will grab the tube, and turned it while pulling out. Some heat might make it come out easier as I believe it is glued in place. I did this over a year ago and i am pretty sure I had to drill the case to accept DSN's tube as my Josh case was a smaller diameter. If I could remember the drill size I would share, but i cant for the life of me remember what size it was. I used some 30 min epoxy on the DSN tube to make it water tight and keep it in place. Good luck with your project, I feel it was worth doing.
One suggestion for you tho, why not wait until T's crowns are complete. I am sure they will be very nice and are supposed to fit the standard rep tube without modification.