If Rigby could stuff 416 Rigby cartridge into Harry Selby's standard Mauser action (and apparently they did it as he sent it back to them at one point to be rebarrelled), then I'm sure they could do it with the shorter and less pressure 350 Rigby cartridge. That, I think, would have made more sense. I also think this is an attempt to go after the nostalgic novelty crowd. Nothing wrong with that. Gunmakers do it all the time (e.g. Browning). Often it's just a flash in the pan that barely, if at all, pays the cost of retooling. Practically speaking, the caliber choice in that action doesn't make a whole lot of sense to me. Same bullet as 35 WH and about same amout of gas. I see no advantage to having a longer action and heavier gun. Mind you, I am no advocate of lightweight guns but a "lightweight" medium bore rifle that's as heavy as a DGR thumper magnum? Why? And I'm sorry, I just don't see this gun being a big drawing card on this side of the pond. Hunting for moose and brown bear is supposed to be rough stuff. Stainless and plastic rules in the Great White North.
If you want one of these cute baby thumpers, I suspect you should order it now. Rigby will probably drop it from the lineup in a couple years ... or sooner.