Thanks for the mention of magazine length and COAL limitations, for those that brought it up.
I thought about the Mauser action length after posting, but then got distracted by an angry 3 year-old ... and I've been out hunting all day.
The (likely) additional COAL available with the Mauser action should allow just a bit more case capacity - especially with 225+ gr bullets - which will help with approaching (and possibly achieving) the velocity goals.
And, Jevyod, please don't think I'm just 'hating on' the cartridge. I respect .358 Win and think it's a good cartridge. I do have some experience shooting and reloading for one, as well. One of my brothers has one (Ruger 77 Hawkeye), and it has proven to be a good option for big game - and easy to work with, as long as COAL isn't an issue. I do, personally, prefer .35 Whelen (own one, and building another), mostly because of the COAL limitations of .358 Win.
...By no means do I think that "lower powered" cartridge are useless. I spent today hauling around a Marlin 336 chambered for .307 Winchester (not an original - I built it from spare parts and a reamed .30-30 barrel). To .308 guys, it's "barely better than a .30-30". To .30-30 guys, it's "no better than a .30-30".
It 'suffers' from relatively low chamber pressure and the necessity to run RN or FP bullets for the tube magazine. And the throat design doesn't get along with many bullets.
It's basically a one-trick pony: 180 gr bullets at 2,500-2,600 fps.
My '06 is "better". My .35 Whelen is "better". Even my .243s could be argued to be "better".
But it's good enough for the game that I chase with it.
As for Ramshot powders...
Have you considered investing in a copy of Quick Load?
I have found it to be very useful. It is of most value when working with my wildcats and obsolete cartridges; but it is generally more reliable and accurate with predictions for more common cartridges.