CZ Custom makes threaded barrels for the CZ 75. It would be worth while to shoot them an email asking them if they can help you. I am not aware of a functional difference between pre b and b model CZ 75 barrels if there is one, although I've never done a side by side comparison. As to the fitting of the barrel I feel that is unavoidable if you expect an accurate, reliable, and safe firearm in the end.