A look to ballistic tables shows You clearly, that the powerrange of the 404 Jeff. has lots of brothers around. I think the love for 404 Jeffery comes from the idea, that if You own one, You can walk on damned old tracks, hunting like the guys did 100 years ago out there in the bush.
The one who chooses the 404 as a new or custom gun has to pay the price caused by the long shell and so longer action means more expensive parts and work. If You get on the end something which is worse the price, I wouldn't bet.
If You finally have one, You'll spend plenty of Your time getting hold on brass, and if available for terrible high prices. The bullets are also not stored in every gun shop. I know that cause I do shoot .423 bullets as well.
If You dream about a gun in this range, look close at the 416 Ruger or even 416 Taylor, which do fit both in standard lenght actions, brass is easy available and 416 bullets are all over. For a gun in this calibers You are very much south of $2k!
Also ballistics of both do much better than the old pearl 404 Jeffery. Decide if dreaming or shooting and hunting ?