So if I understand correctly, I would need to buy 450NE cases, and neck them up to fit in either .483 or .488" bullets ?
Yes. But you'd also need to find un-obtainable brass if you ever intended to hunt in Africa where you need correct headstamps. You'd also need to find a PH that will let you hunt with a hammergun, not all will.
You'll do a chamber cast and slug the bore to figure out what you'll need. You'll mail the chamber casting to CH4D in the States and within 2-3 years they'll make you the correct dies for your chamber and bore, provided you also have brass already so we can determine the neck thickness of the brass so the custom dies size correctly. You can then use your imagination on how to smuggle those custom dies from the USA to the EU.
You'd also need a miracle to find the supplies of the correctly supplied softs and solids Woodleigh (only woodleigh?) made last about 15-20 years ago. I saw two boxes of 50 that sold for $250-$300 a box.
Once you've exhausted the global supply of those scarce woodleigh bullets, turning over as many rocks on 6 continents as you can, you'll have yourself a really attractive wallhanger.
Also keep in mind, there is surely a guy out there with a $125,000 best grade 475 that can't find bullets either and he'll be much more likely to take the box of obscenely expensive bullets than you will if he sees them.
Never voluntarily buy an obscure Nitro cartridge rifle of mid-grade. If you're buying the finest known example, I get it, you spent 6-figures on the gun and therefore why not spend 5-grand and hundreds of hours of your time locating brass, bullets, and dies that are perfect. But for a hammer gun? For an affordable hammer gun? Sounds unpleasant at every turn.
Or, another option that is more pleasant?
