OK, thanks. This barrel was drilled a few inches from the breech, just in front of the chamber. About .730" diameter in front of the hole.
I've converted a Cooey-Carcano to 7.62x39, by unscrewing the 6.5 barrel from the bushing and threading a piece of .303 barrel to suit. Didn't make a note of the diameter.
It would require a custom bushing to use this barrel in either a Carcano or Lee Enfield. 11/16" would work.
Or I could thread the hole, install a plug and line the barrel to .22 for a No. 2 Mk. IV project. The bore seems to be quite decent, thought it might be good to put it to use.