i suppose i'll just use 0000 steel wool on the receiver and parkerize it.
OK, I'm not a complete traditionalist, I'm ok with scopes on lever guns, and I'm a fan of oversize rubber grips on my Ruger SAs.
But, Parkerize a Mauser??
gasp, spit, choke, (why is there no "vomit" smilie???)
No, sorry. Might just as well go get a can of Krylon and spray paint the whole thing....
I won't say it's blasphemy, but its just ....wrong...
Its your gun do as you want, but always remember there is a difference between what you can do, and what you should do.
I've had sporterized Mausers in calibers ranging from .22-250 to .458 Win Mag. Built several, myself, finished the build on others. Never parkerized any. Mausers should be blued.
'
Your "bottom metal" appears to be a commercial after market part. I doubt its stainless steel, more likely regular carbon steel "in the white".
If your VZ were a complete rifle in "GI issue" condition, I'd say don't touch it. since its just the action, do whatever floats your boat. Parkerize it and put a plastic stock on it, covered with rails, its your gun, do what makes YOU happy.
I might puke at the result, but you aren't making it for me....
40, 50+ years ago we used to sporterize everything, Mausers were the best, but we did it to everything, because the military rifles were cheap, and we could make a good rifle, or a fine rifle, as good as any Remchester, (often better) for the same, or often LESS money.
That is simply not possible today. The money part, for sure.
A word about "matching numbers", few nations were as detail obsessed with their small arms as the Germans. Nobody cares much about "matching" parts (other than period correct) in the guns that didn't get half their insides stamped with the last 2 digits of the serial #.
Not having matching numbers doesn't make the gun worthless (no or almost no value) it just makes it worth less (a lower value than maximum) to collectors.
A bare action has no collector value (today anyway), so, nothing lost there.
Good Luck with your project. If you have questions, ask. Odds are good that someone here has experience with whatever it is you have questions about.