Rich - Check out Whelen Brown's site @ 35 Caliber.com. There is a lot of info there on bullets and thier performance.
I have both the 350 mag. & 35 Whelen. I've loaded the 200 Horn. SP, 225 Sierra GameKing, 220Speer FP, and some older 200 gr. Core Lokts - marked 350 SPCL. I suppose Remington made these a little thicker for the 350 mag. and that is why they are marked that way. Any ways - these all shoot about the same in both rifles, The Sierra being a little more accurate. These 35's are a lot of fun to load for and a lot of fun to shoot. Enjoy.