I have a #1 in .400 Jeffery, another great old rimmed cartridge. I like it because it packs a decent punch in a lighter and lower recoiling package than my double in 470 NE.

It's another all 'rounder you can use on say elk, moose or heavier plains game but not feel undergunned if something bigger and/or badder shows up.

Bullet availability isn't bad either, because if you want to use something lighter than the tried and true 400 gr loads, as Grenadier has pointed out you can go down to 300 to 350 gr tips designed for the .405 WIN. And Hornady now produces relatively cheap factory ammo.

If you want something with a little more oomph, I have always thought a single shot in .500/.416 NE would be pretty cool, too. A little flatter shooting than the .450/.400 3 inch.

Either of these calibers would fill "the gap" between your .375 and .450NE.

As you may know though from having your .500 NE built, not all numero uno actions are suitable for the biggest bore chamberings, if you should choose to go that direction again. If your frame started out life as something like a .458 Lott or .416 Rigby with a heavy contour barrel you could build up to a .577 NE if you want to go crazy and have a dedicated elephant gun.

All that being said I still kinda agree with Daryl S. I hear where you're coming from, downloading the .450 NE, but everybody should have at least one .45-70 in the vault. In a No.1 you can get maximum versatilty out of that old war horse of a cartridge.

Regardless, it's great hot stove league stuff just talking about all the potential choices. All the best.