I am quite fond of the 358 Norma Magnum chambering, although I personally feel the bullet manufactures (Hint: Barnes) have slighted the 358 by not offering adequate heavy for caliper bullet offerings.
Years ago I came across quite a bit of unfired Norma Brand 358 Norma Mag Brass and completed ammo. I also have 5-6 boxes of premium 358 bullets, (Swift A-Frames, Nosler Partitions and A Square Lion Loads). I have the Norma 358 reloading dies. There are sufficient components and completed ammunition for 300 rounds or so.
I recently purchased a new Winchester Model 70 Extreme Weather SS rifle, chambered in 338 Winchester Mag. This is the fluted barrel stainless version and at present it is unfired. I've topped that with a Schmidt and Bender 3-12 by 50 scope. It is a very nice rifle. (I own a matching rifle/scope combination chambered in 300 Winchester also) I have zero 338 Winchester Mag ammo for this rifle.
1. rebarrel the Winchester Model 70 frame with a custom barrel chambered to 358 Norma
2. have the original barrel re-bored to 358 Norma chambering
3. Keep the original rifle configuration and merely purchase the danged 338 Winchester Brass, Bullets and Dies