I have a set of CB 750 barrels, removed from my 1972 K2 when I carried out a top end overhaul. They were replaced as a matter of convenience, so that I could have all parts ready for refit without waiting for engineering work/parts if it was needed although in the end, the original cylinders were standard size and seemed ok for reuse. Since removal, the barrels have been stored in bubble - wrap in the garage.
If its 750 K2 barrels that you need, send me a pm for further details.