That is what I had gathered from reading posts here. Now, about my second question... You are talking of buying a custom rifle, commissioned build, or as you would say, "bespoke". So I assume you want to build a keepsake, an heirloom, personal, and hang on to it.
I like the same sort of things, but build them myself, find an old one and restore it, of find one in superb condition and just buy it. I have often been able to find something exactly like I craved for years, built for or ordered by someone with similar tastes. Most of them would have been, for me, unaffordable to build today. A lot of the nicer gun retailers seem to have a steady flow of trade ins or estate sales. Westley Richards, Holland & Holland, Churchill, Beretta Gallery, Rigby, and a host of individual dealers, have fine rifles from the Golden Age of safaris passing through their hands all the time. Even better deals are found in estate sales and auctions, or even through the attorney handling the settlement of affairs.
A very affordable and practical alternative is buying a Sako, Winchester M70 Express, or Remington C grade, and restocking it to perfectly fit you, if necessary. All three of these also have several aftermarket synthetic stocks which are more suitable to a wet environment such as British Columbia, Alaska, and tropical jungles. The Winchester M70 in .458 is a nice rifle, very smooth, really good stock ( comb a bit high and thick for iron sights) for less than $1,000 US.