JudgeG:
Glad to hear you have acquired a .400 double. I have been hunting with one for quite a while now, pretty-much exclusively except for a few forays with a .577 Light Nitro! Mine is chambered for the 3-inch cartridge, which is entirely 'pukka' for a Jeffery double of course. The cartridge is fabulous for big boars and buffalo bulls, and the rifle in my custody is definitely responsible for the greater part of past successes. Here's a couple for your interest:
http://www.hotkey.net.au/~orrs/OctoberHunt.htm
http://www.hotkey.net.au/~orrs/JefferyStory.htm
http://www.hotkey.net.au/~orrs/LongShot.htm

We all look forward to hearing about your inevitable success at Camp Cooley! Meanwhile, here's hoping the .475 N.E. and .375 Express end up with worthy new owners.
Cheers