If you're good with push feed, take a look at the Pure Precision Summit action as well. It has a 75 degree lift on a two lug design, tool-less bolt disassembly and an integral lug. I used one for my .300 Win Mag and have been very happy with it. It's just a simple, well executed action with minimal frills or options. They're $1k regular price, but I see them on sale as low as $700 a few times a year. It should be long enough for a .416 Rem. without modification. I like it enough that I have a 6.5 PRC build in progress using their SKLTN action which should be completed in a few weeks. They're not particularly smooth out of the box, but broke in quickly with some cycling and lube and are quite nice now. I haven't used an ARC action yet, but I'll probably do my next build on their CDG. That will be a target rifle though.
Defiance is now offering some of their actions with a 75 degree bolt. They also offer a 3 position safety and some version of CRF, though no longer with the claw extractor. What I'm not sure of is whether one can get all three of those options on the same action. I've been very happy with my Rebel with the 3-position safety. Mine is push feed and has the 90 degree bolt. If the 75 degree were an option when I bought it I'd have chosen that instead for better scope clearance.
FWIW, all of the above rifles have hinged floorplates, so I can't comment on how these actions do with a detachable magazine, though I can't imagine any insurmountable problems.
I just bought a Peak 44 Blacktooth to upgrade the stock on my Defiance .308. It's at the gunsmith right now to have some inletting work done and get bedded. While it's a really well built stock, it's also very light. It's advertised as 20 oz, and that's what mine weighs. That's exactly what I wanted on my .308, but I'm not sure I'd want it on a .416. It may be sturdy enough, but I'd want some more weight. I'd be looking at McMillan or Manners for this. The traditionalist in me would go for the McMillan Safari. Not traditional, but it has the profile. The .300, 6.5, and my .223 on a Kauger action all have AG stocks, but I don't believe that AG warranties their stocks for dangerous game calibers. Regarding the Foundation stock recommendation, I haven't used one yet, but considered one for the next build. They have developed quite a following and look to be excellent, just be aware that they tend to be very heavy; in the 5-6 lb range for the ones I looked at. This may be a good thing or a bad thing depending on your goals.