Like others have suggested, I wouldn't go with surplus parts. I would buy commercial bottom metal. Everything about it will set you up for higher chances of success in the long run. But if it isn't PH bottom metal, expect to do some fitting.
PTG used to offer bottom metal, and still might.
Sunny Hill should still offer bottom metal.
Sarco occasionally has commercial Mauser bottom metal.
There are plenty of places to check and/or keep an eye on.
As mentioned, just be sure you know exactly what you have, so you have a better idea of what to be searching out.
Mauser followers and springs are pretty universal and generic. Even if you find something that isn't quite an exact fit, it is probably within filing distance. (5-10 minutes with a hand file or grinder should get it there.)
They're so generic that I gave parts to a Jap Type 38 owner to see if they'd work. They're still in the rifle, because they work flawlessly. So, his Jap 38 has 1893 Mauser follower and spring in it.
A couple of points to keep in mind, followers made for the military rifles often have a square shoulder at the back, so that the bolt locks open when the rifle is empty. Sporting Mausers don't have that, its a PITA in civilian use.
I used to think the same thing, since you had to depress the follower every time you closed the bolt with an empty mag.
Then I started shooting bolt guns in timed competition and found myself wishing I had notched followers to remind me when I ran dry. Distractions, bobbles, feed issues, complicated stages, having to reset on the clock, making a mistake with 'hit to move on' targets, and more, can cause someone to lose track of round count pretty easily. There's a lot to focus on. Round count is usually one of the lowest priorities.
Yes, this is mostly speaking for myself, but I've seen plenty of other people do it, too. Case in point: Our last match had two stages with weird target rotations (and one of them had a time bonus), where safety, the target rotation, and dope for each distance, was about all a person could focus on. Nearly every shooter finished the stages in the same manner: Closing the bolt on an empty chamber, opening the bolt after feeling that nothing fed from the magazine, looking into the ejection port, doing an awkward prone twist to turn back to the rest of the squad, and asking, "That was it?"
Heck, at this point, I wouldn't mind notched followers in my commercial hunting rifles. Not that it has happened to me in a very long time, but, "You're empty, idiot," is not a bad reminder in the field, either.
