Take a look at the gun's receiver for the manufacturing date, it's a 2-digit number. If it's actually stamped 57 or 58, it more than likely came from the Czech factory chambered in the shorter Soviet 7.62x39 round. The VZ-52/57's draw a higher price than their older VZ-52 stablemates, chambered in the 7.62x45 round.
Chamber inserts are bad juju, no 2 ways about it.
Century Arms decided to hide a multitude of sin by slathering that black crinkle pait all over the VZ-52's they sold, even covering the metal heatshield of the handguard. After stripping off the paint, cracked, dinged, or broken stocks see the light of day.
Great American Gunstock Company in Yuba City, CA, sells walnut reproduction stocks and handguards for the VZ-52 and VZ-52/57 rifles.
Surplus 7.62x45 ammo is still out there, albeit corrosive and non-reloadable. Some enterprising individuals, myself included, make our own 7.62x45 brass from .220 Swift or 6.5x54 Mannlicher-Schonauer donor brass. Easy to do, and the gun does quite well running 123gr AK bullets in the reformed cases. They actually do better than the AK for groups at 100 yards, too. The rifle is a pussycat in either chambering, with it's heavy stock, long barrel, and unique gas system.
Here's one website that speaks at length about the VZ-52:
http://www.mauser98.com/vz52.html