I have no idea if Simspson's checks headspace. If they say it's a 9.3 x 57 it is. They do check the cartridge intended as some of the 9.3x57 rifles rechambered to 9.3x62 are listed as such.
It won't say headspace dimensions on the barrel. Manufacturers only list the cartridge or caliber.
In Husky's case they only marked 9.3x57 rifles with "9.3". A designation of x57 or x62 is a case length designator for a cartridge, not Headspace dimensions. We assume the rifle left the factory at CIP or SAMMI spec. However, there was no CIP or SAMMI spec for the 9.3x57 until last year.
The long chamber is pretty common in the 1920s thru 1930's M46 small rings.
You can use 8x57 gauges to see. If it closes on the 8x57 Field Gauge you have excessive headspace. But if it doesn't close on the Field Gauge you're good to go.
You need to read Daryl's write up on creating a false shoulder to fireform his 9.3x57 brass to his chamber After you do that you only neck size so you don't push the shoulder back again.

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=179514&an=0&page=0

Don't loose sleep over it, just check it before you shoot. Billybob on the internet got his information about headspace from his cousin's girlfriend's grandpa's dog. Just check it with the 8x57 Field gauge and if it won't close, go shoot. If it closes on the Field gauge come back and let us know.

Just to see what would happen, I fired a mild 8x57 handload down a crappy bore M46. Case formed perfectly, even the neck!. The bullet was only about 6 inches off the bull at 50 yards. Don't try this at home kids etc etc. My attorney makes me state that 'cause we know someone is going to do it.