I do know the .416 rem I think had some jamming problems back in the day, really not a fan of the .416 rem, but a the .375H&H and .458 Lott are clear choices,

The .375 Ruger, and a .416 Ruger would be a great round I think.

I'd be surprised if they offered anything over .375, I just really want a model 70 in .375, the fact that they don't offer one is kinda surprising to me. I know probably way more guys want 300's, but the model 70 action is a great reason to buy a big game cartridge.....ie .375

and of course a double rifle is the way to go......course I'm not sure how many guys are willing to go from $1500 to $15,000! for a cheap double? only alternative is a mauser 98, or model 70 action ....so for now a bolt action will have to do......not ready for that double just yet.