Hummm -
The real question is if you're willing to settle for less.
The Chilean Famae 542 is an early 540 design licensed out by SIG (Swiss Arms) - the Chileans never changed / upgraded their design or production line.
The Swiss Arms Black Specials / Classic Greens are built of the FINAL incarnation of the 540 (just the first mandril of the 540 production line is used - the Bolt, Bolt Carrier, Barrel, Gas System, and furniture is off the 55x production line).
The final version of the 540 receiver mandril is virtually identical to the 55x (the three rnd bulge on the 55x rifles are produced using a second mandril, the different internals of the 55x line is created by a sleeve fitted / soldered, then welded into place).
Soooo - do ya really want to purchase a new 'old' rifle?
Abby