The other gun that maybe meets the bulk of the OP's specs is the Fabarm Classis, english stock, ejectors, oiled finish, 3" proofed for 1350bar high pressure steel ammo, as per new Euro standards, interchangeable chokes, 28 or 30" barrels, but, it is an SST, and they are not CCH'd. Don't knock the SST's, may not be "traditional", but they work just fine, and they've been around for 100yrs plus too. Ran one since 2014 now, case and 1/2 or so every year, of 3" bb's and #3 at 1450, shot likely a case of the 1-1/8oz 1550fps loads too, zero issues other than LH ejector needed fixing after closure on a pea, my fault, I forced it. Shot it in rain and snow too.
Korth is dist for Fabarm up here now, Classis not listed on US site, have to go to Italian site, although, I think US has the 20ga Autumn, same gun, different dressing & DT's. Boxlock will run around 3500, sideplated ClassisIV around 6k.
Other one I use is a FAIR Iside Vintage 20ga hammergun, same as Cat's, no beefs. FAIR is not as well finished as the Fabarm. And the Fabarm chokes have to be patterned to believe what they do, their Mod is perfectly useful for snows at altitude or at the edge of dekes, far better than my SBE was.