Ruger--yes, going to Africa in 2013, plains game, kudu and gembok on the menu, eventually I plan on going back with eland and zebra on the menu. I thought this would be a nice gun to pick up since I plan on going for grizzly at a later date also.
Good caliber, if you handload.
If not, you are very limited in factory loadings(With only 2 of the 3 suitable for plainsgame hunting).
Any .300 mag is more than enough for what you have listed. It is also what I have planned for this year and will be done with a .300Wby and a .257Wby.
I don't handload, figured the 270 grain bullet would be fine. I have a 300 WSM and WBY, both shoot great, it's just that I found this gun that's kind of rare (laminated stock stainless) and thought I would pick it up because eventually I want to go on a griz hunt.