The L1A1 barrel is not terribly difficult to make up from a blank.
Yes, a bit, well, a lot, more fiddly than your basic bolt-action sporter, but not totally horrendous.
Back in "The Good Old Days", serious (and slightly sneaky)
Australian shooters would get a quality blank, like a Schultz and Larsen or Mc Millan, and get it profiled and threaded to suit. Gas blocks were usually fitted AFTER the barrel had been wound into the receiver and the chamber "final-cut". ( This saved a lot of messing around and changing locking shoulders). The keyway for the flash hider retaining washer was also milled after final fitting, ditto the gas port. "Pre-loved" Omark rifle barrels, especially the "Black Mountain" variety were popular as well, especially with the "less well-heeled". I know of two L1A1s that were built in .243 Win: These needed a MUCH smaller gas port in the barrel due to the much higher bore pressure at the port. You could go nuts and build one in 260 Rem or 7mm-08 if you wanted.
Another benefit of such custom re-barreling was that you could leave the rear of the barrel (the part under the handguard) fairly "beefy" and still JUST get the furniture on. This definitely improved the shooting and certainly moved the balance a bit further forward.
The absence of bore and chamber chroming was of no real account, as most of these rifles were only ever fired at nice targets in fine weather, and with the best ammo the shooter could afford to buy or assemble. (We are not talking about "official" military shooting here.
With such a barrel, with the fit of the receiver components "tweaked", and Hythe" sights fitted, these rifles were seriously accurate on the range, or in the field. Add one of the original Hensholdt scopes or similarly mounted commercial glass and they were real screamers.