If you want CRF in a left handed action, Montana Rifle actions are an excellent choice they are backordered right now at the factory, but should be shipping any day. They will handle the 458 lott or the 416 Rem but not the 416 Rigby or 460 Weatherby. MR also sells barreled actions and has gunsmith services.
I have a Win mod70 416 Rem that I love too shoot, it is a great Buffalo rifle, but it is not a charge stopping rifle. If you are willing to trust someone else to pull your bacon out the fire if [censored] hits the fan then the .416Rem or Rigby is all you need. I personally prefer to know that I can handle what ever happens. If there is a wounded animal to follow in the thick stuff heís mine to sort out the PH can back me up. This might not be for every one, but if I pay $10,000 and travel to Africa itís not to watch a PH shoot my animal.
Also the H&H based cases have a larger Magazine capacity than the Rigby or Weatherby cases.
BP-Tech makes a muzzle break that does not increase the noise level, and is tunable for muzzle lift.
Montana Rifle Co