I think you did well, nice looking old mauser at a nice price.
The phillips head screws definately mean it was updated some later on, I don't believe they were used much before 1940.
It would be a good idea to slug the bore and do a chamber cast before obtaing any Ammo or components.
I picked up a similar old sporter awhile back and mine will require the .318 rounds M88 specification because of the bore size and tight neck.
Read these two threads if you haven't already.
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=300670#Post300670http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=300512#Post300512