Rachel: thanks for the pictures, that is a nice looking rifle. From the looks of the action I would say it is a K98 military style action with the bent bolt as the action and stock have a cut-out for the shooter to use his left thumb to strip rounds from the stripper clip into the magazine
The rear sight is a US or European aftermarket (there was a preference, in earlier yeras, for flip sights for short range and long range leaves) and it looks to be sweated in place on the barrel. I could not tell however if the barrel is mil-spec, with cooling steps or if it is a round sporter barrel. If it is a round sporter barrel it is either a pre-war sporter model or one of the few military variations that came with a round non-stepped barrel. I would like to see a picture of the barrel and the front sight, if possible, to see if there are any 'cooling steps' in the barrel and what the front sight looks like.
The stock certainly has some nice artwork to it and the 'perch-belly' stock makes it a sporter as I do not believe there was enough wood on a mil-spec stock to give that sort of drop to the comb.
Those 3 holes are for some sort of a European mount, and the Ajax scope mounting system comes to mind. You or your friend may need to look to European scopes and mounts for information as I do not recall any US mounts using 3 linear holes, but I could be wrong and I will need a 'real' Mauser expert to clarify this for me....
Also, where the screw holes are - does the lettering read Model/Modle 98, or Model/Modle 88??? Thanks.