Joe -single barrel options for these two can be had for only a couple of thousand dollars. As opposed to the tens of thousands for the doubles.
Upside is they can be loaded any way you want, the 700 nitro over 2500fps and 14,000 ftlbs.
Downside is they need same weight as a 50Bmg to handle this sort of recoil, and of course that they are not a 'double rifle'.

Karl.

Although I am most definitely biased, If you really want something similar to either of these in function do a search on the 600 OK. No Nostalgia here but a ballistic duplicate of the 600 NE, (and much more if you dare) in a multiple shot bolt action rifle and it can be done for under $5k
JMO

I agree, go .600 OverKill.

I shot mine again today, report to be posted later, at work now.

The .600 OKs just loafing along at either .700NE or .600NE power levels. Although this level of power makes for fun practice loads . Go .600 OK!-Rob

Farqharson or Hagn 700 NE:

700 NE: 1000 grains at 2000 fps

600 NE: 900 grains at 1950 fps (except Jeffery loaded it to 1850 fps)