RE: mauser question
As posted above, there is no one answer. Kind of a "it depends". Do you have any tools? Do you have any ability to work with tools? What kind of mods will you be wanting? Shortened barrel? Scope mount? Rebarrel to another caliber? To have somebody do these things professionally, you will end up spending enough to buy a very nice ready made sporter.
Building sporting rifles from miltary surplus rifles is not really cost effective today. You can buy a Savage and a pretty good scope for $450 to $500, maybe even less.
Your sporter is going to cost at least as much, by the time you drill and tap, cut off and install a new bolt handle, install a new safety,cut and crown the barrel, possibly restock and bed the rifle. Add in the scope mounts and rings, and a decent scope, and you are talking the same amount or more.
Not saying don't do it, I've built several rifles on 96 and 98 actions, and it is great fun. Nothing feels like hunting or shooting that sub MOA groupwith a rifle you built. Just be sure to go in with your eyes open, that's all.