Your rifle started life as a Kar98a carbine, not a full length rifle, and it has been heavily sporterized.
The receiver "ring" is the part at the front of the action where the barrel screws in. A "large ring" is 1.41" diameter. A small ring is 1.3". The "shank" is the threaded part of the barrel that goes into the action. Large shank is 1.1" diameter, and a small is .98"
A typical '98 action is large ring, large shank - beefy for strength. In profile, you will notice that the receiver ring does not appear thicker than the rest of the receiver, like on a typical '98. The Kar98 is a small ring, large shank, meaning that the action is a bit thinner than most. The barrel was also thinner than other Mausers and tapered. The result was a short, handy, very lightweight carbine originally intended for artillery & support soldiers for whom rifle shooting was not a primary task. It became popular with infantry however during the first world war.
Surplus Kar98's were a popular choice for conversion into hunting rifles for the same reasons, but there simply aren't as many out there as the standard "large ring" 98 action, so you may be limited in the choice of replacement stocks. Possibly custom order, if anyone will do it. The stock you have looks pretty good as-is.