I have had some .303 barrels rebored and rechambered to 8mm by a gunsmith in Washington State... Beautiful work... not sure if the dimensional difference in the .303starting barrels will work with your receiver though. Might have to have them made new... originals are rare on the open market and quite coveted here in the US... I've been looking for a few years now... but I don't get out to the full auto events where they seem to hide.
Wally, who did the work? I'm sitting on a couple thou 8mm, would give me another option other than .303.