The 358WSM is very similar to the 350 remington mag. Just a bit more case capacity. I have great results using TAC in the 350 remington mag. I run 60 grains under a 200 grain Barnes TSX. This is out of a remington model 7. I am limited by mag length. So 60 grains is about max. In your case you could probable work up a fair bit more.
The other load is a 180 grain Barnes tipped TSX with 64 grains of TAC. This is in a Ruger MKII. Was built on a WSM receiver and was also chambered long. Factory just got lucky. Anyways I can load over max oal and have more powder capacity. You could probable go a bit more than this in the 358WSM.
TAC gave me the most speed of any powder I have used in the 350. Would think you should have similar performance in the 358 WSM as the cartridges ain't much different. Don't have the exact numbers handy but the 200 grain were running 2600 fps ish. The 180s were right about 3000 fps.
