Frankly I don't think it's worth swapping on a repro for shooting unless you're going to be rolling in the mud with it as a reenactor or there is a known problem with the original stock (e.g. a bad crack) that makes you afraid to shoot it.
Old stocks hold up fine. On a G/K43 I'm much more worried about the gas system, bolt, and the receiver as far as damage from shooting than I am the stock.
Plus there are a lot of fiddly metal parts in the stock that I'd be very wary of screwing up (either the metal or the wood) if I was swapping the hardware over. No way I want to remove the recoil lug or touch the band spring, for example.
The other reason I hate swapping stocks is that this is how stocks end up lost. Lots of guns out there where someone swapped a few parts and put them in a drawer then they die or get divorced or whatever, their stuff gets sold, and the parts never get reunited.