I ask questions here to cultivate that kind of info, trying to piece together data can be a pain! So many of the people here have enormous amounts of info, and the gun community is slowly losing this knowledge as the old timers pass on. I am one of the more knowledgeable gun guys in my circles, and I don't even know that much!
I have been curious as to how much better the 95/96 Mausers are than the 93. I have had a few 93s and a few 98s, both a commercial one and a couple surplus ones. Never had a 95 or a 96 to play with though...
For an overall comparison of the different Mausers, Jerry Kuhnhausen's Shop Manual on them does a good job going from part to part comparisons with quite a few pictures. His general observations were based on numerous conversions and rifles coming through his shop during the great heyday of military surplus.
These are simply my observations and I have examples of the 93-98 Mauser models and some others as well and restored some of these to military issue condition.
The 1895 actions were German built and display finer workmanship with a round bolt and a bolt handle lug recess in the receiver. They were made by Ludwig and Loewe (these are antiques). M95's were exports to South America, particularly Chile in 7x57 Mauser and possibly some other countries (South Africa during the Boer Wars). There is an 1894 Mauser design for 7x57 that were exported to Brazil as well that are generally in pretty bad shape which I believe also used a round bolt but no bolt handle lug recess in the receiver while the chilean mausers are usually in pretty good shape.
There are some variants of the 1893 Spanish Mauser including the most common, the 1916 models. Some of the earlier ones were made in Germany, I believe from the Oberndorf factory but I do not discount the possiblity of DMW or Ludwig and Loewe made ones. Pretty much all of these used an early squared bottom bolt that was designed to feed better--it didn't. The Spaniards set up Oviedo arsenal for Mauser production pretty early but not sure that any of those made it to the New World in time for the Spanish American war. My personal impression is that the Oviedo products are of softer steel by an large and do not demonstrate as high workmanship on fit and finish as do the German or Czech makes. The Swedes, by specifying their steel be used, demonstrate high levels of fit and finish regardless of whether they are the earlier German make (Oberndorf factory) or at the Carl Gustaf's state arsenal (some were also made around WWII by Husquavarna that are of very high quality). The Swede bolts will not fit in a non Swede action btw due to cartridge differences.
The Swede cartridge and its oversized case head (.480) compared with the 7x57 (.473) is one difference along with the Swede generally being slightly larger in diameter measurements at the base, shoulder and of course bullet with a shorter cartridge case. The Swede also had a marginally higher pressure than the 7x57 issued at the time (this is one of those areas where experts dispute exactly how hot issued ammo was around the turn of the century--it is not helped by the fact that the early smokeless powders often demonstrated quite wide variance in pressures and were temperature sensitive--so that a 7x57 fired in a warmer climate might be higher in actual pressure than a 6.5x55 used in a relatively cold climate despite the nominal cartridge specifications).
Slamfire, a THR regular has some long informative threads on this and other boards involving steels and heat treatments of the various Mausers and Springfields of the era.
http://www.hoosiergunworks.com/catalog/mauser_reference.html
Now, as far as the .458 SOCOM goes, it looks like you could do such a conversion, it would take some work to adjust to a detachable magazine or to use the fixed magazine and would require some sort of blocking--maybe feed rail adjustments. A Spanish, Swede, or Chilean Mauser should be able to take the pressure as specified.
Rhineland arms has one demonstrated in .450 Bushmaster which is close to what you want which uses a barrel nut system, ala Savage type, to adjust for headspace.
http://www.troupsystems.com/product/mauser-450-bushmaster-bull-barrels/
The Rhineland Arms conversions might give you some ideas.