Not many off the shelf stainless 375HH options at the moment. The one you are most likely to find is the browning xbolt. The Kimber talkeetna and the m70 stainless classic are about as good as it gets for factory rifles but good luck finding either one of those. The m70 is out of production and the talkeetna is tough to find. Kimber just moved and I don’t know if they even did a run of talkeetnas yearly as it was.
If you can find an older stainless Remington or an xcr/xcr2, those are good, especially if you send the bolt out to get welded up. If you look around you might be able to find a m70 stainless classic but it will probably be close to 2k in today’s market. I found one a few years back and paid like 1300 dollars for it, I thought it was a score.
I’ve been all up and down this and the bottom line is that you can buy an xbolt, search patiently, or go with some sort of a custom. Your only other choice is to get a 375ruger. Ruger, savage, gunwerks all make those.
I may be forgetting a thing or two but options are very Limited for stainless 375HH rifles at the moment.
Another option would be to look for something in 338 win mag, you might have better luck.
Edit: you might be able to find a sako kodiak on gunbroker, thats stainless with a laminate stock.