You could also try starting with an 0-6-0 switcher mechanism - the Bachmann saddletanker has appropriately-sized drivers and the proper slide valve cylinders. You'd need to lengthen the frame at the front of the loco, a fairly easy task, then find another boiler/cab. Bachmann sells many of the parts and sub-assemblies for their locos separately, so you may be able to get a cab and boiler for one of their Ten Wheelers, too.
Modify locos often requires a lot of research, not only for prototype info, but also for info on models no longer made, but still available from various sources.
You'll also require tools beyond the usual modeller's toolbox, including hacksaw, vise, mill files, and soldering irons and torches. You should of course have a fairly compete set of modelling tools, too, including X-Acto knife (knives), pin vise with drills, some common-size taps, needle files, screwdrivers, calipers, scale ruler, razor saw, jewellers saw, motor tool with cutters and cut-off disks, various pliers, etc., etc. You should also acquaint yourself with the catalogues of various parts suppliers, including (but not limited to) Bowser, Precision Scale, and NothWest Short Line.
If you've not done this kind of work before, I'd suggest that the loco you've chosen may be too ambitious a project for your first foray into loco kitbashing. Instead, how about a prototype that you like, but of which a suitable model exists as a starting point for a "detailing job"? Loco kitbashing is an enjoyable facet of our hobby, but much of the skill required is to be had by hands-on experience. There are lots of us here to answer your questions and offer advice, but it's still a "learn-as-you-go" affair.
Wayne
