As in all old rifles, accuracy depends on the condition of the barrel and the stock bedding.
These fine Mauser rifles are capable of a high order of accuracy when in good condition.
I had an older Guns and Ammo Annual that had an article on why custom gunsmiths preferred the 98 Mauser as the basis of a fine sporting rifle.
The author stated that the German-made Argentine 1909 was the finest quality military rifle ever made.
A look inside will show that these rifles are better finished INSIDE than other rifles are outside.
The author stated that to reproduce the rifle with the same quality would cost around $3000.00 per rifle. This was in the mid-80's
Like most military bolt rifles, the sights are in meters, and the rifles had a factory-set battle zero. This means the rifle will shoot high, so you may want to order a replacement sight from Gun Parts Corporation.
This is an extra high new sight that can be filed down for sighting in.
The item number is 078-050-000.
As for 7.65mm ammo, you might try Samco, Cheaper-than-dirt, or any of the other surplus dealers.