Hi TilleyMan,
there are some errors or misconceptions in your above posts:
According to the 1991 German/CIP proof tables, the .308 Norma Magnum's maximum allowable working/service pressure was 3800 bar, same as for the 8x68 or the various Weatherby numbers. FI the .300 Win Mag and 7mm RemMag were given at 3700bar.
The Brno ZKK rifles were, for many years, the lowest-priced fullbore repeaters listed in the Waffen Frankonia mail order catalog, so they are quite common here. At least since the 1969 catalog Frankonia offered both the straight-comb "standard" stock without cheekpiece and other frills, and the so-called "export" or "luxus" Weatherby-style stock at some Mark60.- more, with MonteCarlo comb, triangular foreend, scip-line checkering, painted-on "rosewood" slanted foreend tip and inlaid white-line spacer. This abominable stock was only available at first on 600 and 601 actions. For a time in the 60s there even was a "Germanic" hump-backed stock with cheekpiece.
The 601, 600 and 602 receivers differ only in length! The barrel shanks, receiver rings and locking lugs are of the same dimensions, so all three are of the same strength and will take the same pressures. There were other reasons why they chambered belted cartridges in the long 602 actions only: 600 bolt faces were regularly machined to take standard 30-06 size rims, so these would need opening up to taake belted numbers. 602 bolts were already set up for belted bases, so it was probably easier to simply screw "magnum" barrels into these instead of making another type of 600 bolt. Further the 600 magazine would take only four cartridges, even after replacing the sheet-metal box, while the 602 mag easily gobbles up 5-6 belted cartridges. So I see no reason not to rechamber a 30-06 600 to .308NM, but there is more work involved: You have to open-up the bolt face, alter the extractor and, to make the thing feed properly, have to make a new magazine box. Zkk mag boxes usually have pressed-in guide ribs in front of the case shoulder. these will be in the wrong place after rechambering, cut capacity even further and impair proper feeding. After all that work you will end up with a rather light .308 Norma Magnum rifle, but that is a matter of personal taste and recoil tolerance.
Stock finish: The Brno people apparently did not grade walnut before machining. So you come across stocks with a lot of figuring like black streaks and fiddleback, and on the other hand very plain ones. There was no difference in pricing, but the plain stocks were usually finished or stained dark, while they left the figured ones more in their natural colour.