Jon
The Whelen has a European sister cartridge but I can't for the life of me remember the designation. It, the Whelen, would make an excellent Boar cartridge.
I found a way to tame down the 458 Winnie, I shoot 350 grain jacketed bullets or load it down with 405 gr lead bullets. Much more civilized. Loaded like that it is a 45-70 bolt rifle.
I would assume the NEF Rifles are somewhat like Thompson Encores and Contenders. You just can't get enough barrels for them. And pretty soon they become addictive. I have 8 Pistol Barrels and 4 rifle barrels.
I wouldn't dare live where you do. I'd have more excuses to purchase multi caliber rifles/shotguns than can be imagined. I'd also be in the poor house.
Don't overlook the Whelen, it's an excellent cartridge and very versatile.
Best wishes, Bill