If it matters, I killed a Kudu with the 100 grain Sierra, lung shot, ran 300 yards, but ALL African game runs when hit, which is unnerving to say the least. I like Bang/Flop, but sometimes, a heavier bullet makes the difference.
To answer the question: "Is the twist fast enough 100 grain bullets?"
When the rivalry between Winchester and Remington over the new twenty-four caliber chamberings, (it's been repeated many times, but) Winchester saw the 243W as an all round rifle and Remington decided it was a varmint round and the 244Remington came out with a slow twist for light bullets on small game. So, the 243 had a 1 in 10" twist and outsold the 244. Remington changed the name to 6MMRemington and went with a faster twist. Don't quote me but I think it went from a 12 twist to a 9 1/2" twist? The problem being, the only 100 grain deer bullet that would stabilize in the 244 was a round nose with a long bearing surface.
Well, ever since then, (and this was in the 50's) the 243W has been factory chambered with a ten twist and the Remington 6MM has a 9 1/2 twist and they both handle 100/105 grain bullets. It doesn't matter if Savage or Sako chambers a 243, they usually go with the standard twist of the original Winchester.
Having said that, I am going entirely by memory and it's possible that somewhere, sometime, Savage used a different twist, but if you were wagering, I'd bet on a 10 twist and it would handle most 100 grain deer bullets. What scares me, a little is you mentioning a Berger hibred and that's not a fair question because these bullets have a different form, short bearing surface and THEY MAY NOT STABILIZE in a plain vanilla Savage 243. But, that bullet does not fit my concept of an ordinary deer bullet anyway, it's mostly for the long range target crowd.
I own a 243 and a 6MM and a 243Ackley/with a 8.5" twist, which is the only one that I use the 105Berger hibred, so I have no idea how it might perform on game. BUT, I think you are barking up the wrong tree, on that one. Good luck, whatever. BB