Damascus barrels can not be easily turned down on a lathe I have read somewhere. The different types of metal tend to tear out instead of cut or shear well. So I think that getting a good clean thread to cut and hold in the barrels may be very difficult. I guess you can find someone to do the job but the chance for a good outcome does not sound good to me. Easier to open the chokes unless the gun is a real collectors item. They made a hundred thousand Ithaca's so unless it is a rare or high grade gun opening the chokes will just make it more versatile.
Thinking back there was an article in Shooting Sportsman a few issues ago about a barrel striker who was making barrels using old Damascus blanks and all the problems encountered in taking a rough blank and striking it down to size and then finishing it into a set of barrels. He is one of the last people still able to complete the job. He almost become some type of Zen barrel whisperer. His work was beautiful and in much demand to those who have accumulated the few remaining blanks to work with.
