There are no current plans for anyone making a SRR Ks-1 class 2-8-0 in O. I've checked. Heck, nobody makes one in HO that I'm aware of, either.
I'm not in 3-rail at all but I'd buy even a 3-rail version of 630's class, as this is the first steam loco I ever got a cab ride on (at the age of 11). My parents saw her in operation countless times as ET&WNC # 207 before she was traded back to the SRR for a Central of Georgia RS-3 (which ironically is sitting within 200 feet of where 630 usually sits, at the shop end at TMVRM. I was lucky enough to see my old friend again in 2012 (31 years after I first saw her), but sadly not in steam:
If I ever got a model of this class, I'd be torn on painting it as 630 or modifying the coal bunker area to make it into ET&WNC 207: