Jon Speed in his book "Mauser-Original Oberndorf Sporting Rifles" on page 275 shows a bore dimension table from the Mauser factory dated 1926. This should apply to your rifle too. Mauser then prescribed these barrel dimensions and tolerances for the 10.75x68:
bore/land: 10.45 (+ .05) mm = .411 - .413"
rifling groove: 10.75 (+ .05) mm = .423 - .425"
Rifling twist, one turn in 420 mm = 16.54"
CIP Maximum bullet diameter is 10.78 mm = .424"
The DEVA handbook gives this pressure tested 10.75x68 load with components available in the USA:
RWS case, Woodleigh .423" 347gr solid or soft nose bullet, CCI 200 primer, 67.5 gr VV N140 powder for a mv of 687 m/s = 2254 fps, pressure at 2956 bar well below the 3300 bar CIP maximum.
BTW, Larry Schuknecht offers good Mauser reproduction buttplates,
http://www.dutchmanwoodworks.com/buttplat.htm
As your rifle was made in early 1924, both the early "WM" and the later "Mauser" type would be correct, as the transition started just in 1924.

Huvius, the 1926 Mauser table gives the same bore-groove diameters and rifling twist dimensions for the .404 too.