Another vote for Wilkinson, I've had several barrels with his choke work and the proof is looking at the choke after being shot, no black blow by on the choke when removed. That tells you how well the chokes actually fit.
The ones mentioned are good....
Another great option is Steve Baldwin of Mechanical Accuracy in Jones, OK (OK City area) Steve is a shooter and great gunsmith and makes a lot of stuff for other suppiers - (405) 399-2875
Randy Mitchell at Seminole Gunnworks in Florida does superb work as well. The thread system he uses keeps the chokes tight without a wrench. Thye don't come loose after hand tightening. Just a plus over some of the others.
I have never been a big supporter of barrel alterations of any kind, that being said the last gun that I bought had been done by Wilkinson prior to my buying it ... I will tell you I am impressed with the way this barrel patterns and the overall density of the pattern it throws ... The Barrel was a big bore barrel from Perazzi and measured .736, now it measure .742 with a .035 restriction (choke) and its reduces targets to dust from the 27 yard line ... The gun is still new to me as I have only shot a few hundred targets with it but its coming around and my confidence level is increasing everytime I shoot it ... I'm a hard sell, but I think I'm convinced after seeing what it can do ... WPT ... (YAC) ...
If I were going to have a new (unthreaded) barrel done it would be with Tommy and a complete barrel package would be done.
If it was strictly and soley to tube a barrel, then Stu Wright would get the nod.
Whomever is chosen make sure they aren't practicing the procedure on a card table at a gun show or basement location and definetly not on the back of a pickup. If that threader is bending, STOP the individual!