I have both and the 350 is one of my most accurate rifles. It likes H4895 & 250 Hornady SP and 250 grain Speers ~ 5 shot groups in the order of 1/2MOA.
I’ve shot my 350 (600) for quite a while. My Classic was new to me last year and now it’s Dyna Bore Coated. I’ve only shot that a little and it looks promising.

I’ve had several 375’s. Unfortunately I’ve only shot them at paper and prairie dogs. FYI: Over penetration is an issue with the dogs.

I prefer classic.
Semper Fi
I used to run with the hare. Now I'm envious of the tortoise and I do my own stunts but rarely intentionally