Would also send an email to Jim Kobe. He knows his way around a 1909 and it won't cost you an arm and a leg. As the extractor holds the rim while loading, the more slope the cartridge's shoulder has, the more potential for smoother loading over the feed ramp. However, I have a number of mausers for improved cartridges (7x57AI, 280AI, 30-06AI) done by three different smiths and they all fed very smoothly. Cartridges longer than what the original mauser actions were intended for require modification to the magazine and/or the feed ramp. FWIW, the 7x57 as is, would be a great choice for that action as it requires no modification and is plenty of cartridge for deer and elk with 140-150/60g bullets. There is plenty of length in that magazine to handle the 7x57's bullet selection for chamber throated to a desired length.
Apparently, I have been fortunate with 98s. None of the work done was expensive compared to some of the custom 700 prices I have seen and all has been satisfying.
