While I'm waiting for my decals I have started to work on #18. I've started with a spectrum consolidation frame and will be kitbashing or scratchbuilding everything else. For the tender I am using spectrum's small baldwin tender. This, of course, will also have to be modified to better represent #18's ( well, actually #14's) tender. I'll post pictures as soon as I get a chance to take some halfway decent ones.
For modeling #14 in HO scale, might I suggest the Bachmann ten-wheelers. They have two models, a "high boiler" and a "low boiler". I think the high boiler is the best bet, because the boiler is nearly horizontal (the low boiler has a much more dramatic step up in boiler diameter sizes as you move from pilot to cab. I have no idea what driver size the real #14 was. I was just about to build one when I switched from HO scale to N/G scale.
High boiler and 63" drivers: http://www.bachmanntrains.com/home-usa/ ... ductId=162
Low boiler and 52" drivers: http://www.bachmanntrains.com/home-usa/ ... ductId=157
In case anyone doesn't know, a good source of A&A decals is MODERN RAILS (google it), owned by Ricky Rupp. A great guy, very helpful, and knows his stuff as well.