A couple more comments:
The Mannlicher-Schoenauer Magnums were based on the 1950 action, the last action with the straight vertical bolt. The action was lengthened slightly (see Stoeger's Shooter's Bible from around 1958 or so for a detailed diagram).
If you plan to shoot a lot with full power .458 loads, you might want to check to see if the recoil lug area needs reinforcing. I see no cross bolts on your rifle and Mannlichers had a very short distance from the recoil lug to the magazine well. I have seen quite a few older MS's, especially in 9.5x57, that had cracked from the recoil lug into the magazine box. A few were split from the magazine box to the trigger cutout and a few were split at the tang where the recoil force over time had split the wood. This can be prevented with proper glass bedding and maybe some internal metal rods perpendicular to the axis of the bore at the recoil lug.
Some purists get the vapors at the thought of these alterations to an original and rare rifle but the alterations are better than a split stock.
As far as the far-forward bolt placement being a hindrance....The Mannlicher's smoothness and a bit of practice should overcome any time lag. Actually I think this argument is more imaginative than real. It reminds me of those folks who try to argue that a short action, in a pinch, is a lot faster than a long action. At the same time the .375 H&H, which requires a very long bolt throw, is heralded as the absolute best all-around cartridge.