Filling in around the two listed, is the 375 a good 1000 yard big game rifle or would it be better necked down to 30 or 7mm or 338? Ive heard its case of choice over lapua and norma for many 338 builds.
The 375s are becoming a better option with all the new bullets. I had quite a few rounds (600+) through my 375 BME before I retired it. I think the 338s are still about the best option for 1000 yard hunting. For this build I'm not really looking for a super long range gun, just an all-round hunter. That's how I ended up going down to the relatively small bore options.
I think I've settled on the 270/375 Ruger for this project. I'm just making a couple little tweaks to the reamer specs and I'll get it ordered in the next couple of days. I'm going to nail down the barrel maker as well. There aren't a lot of options for 1-7" twist 270s but there are a couple good ones to choose from.
The next step is settling on a stock. The front runners right now are the McMillan A3 or a Joel Russo sporter. This is the Russo stock

I love the idea of a nice wood stock and I just can't find a synthetic stock that I really like. I'm just not sure how I feel about dragging a beautiful wood stock around in the woods with me.