The old man that taught me most everything I know about turkey hunting shot a Fox 10 gauge with 32" Full/Fuller barrels. I have that old gun in the safe and it is a queen only! I would not even think about threading it the barrels are so thin on the end, but that is just me.
On your Zabala, take it to a competent gun smith and they can tell you if they can do it. Briley will probably do thread the thinnest barrels of anybody, but I tend to shy away from thinwall tubes.