If you go for small 'industrial' narrow gauge, there are a number of more common types that could be seen anywhere, both steam and IC, but virtually all of the public, general carrier narrow gauge lines had their own specific stock. Perhaps the only 'missed boat' is that 2013 is the 150th Anniversary of steam on the Ffestiniog so an England would have been a good alternative (perhaps simpler too) though almost as line specific as the L&B Manning Wardles (though some did on occasions run on both the the old WHR & Rheidol in the early 20th Century).
While the chassis may be useful, it is likely to be expensive. Still, you might be able to sell the spare body!