I've seen the 55n3 stuff before on different forums online. It's an interesting idea, 1:55 scale being right between On30 (1:48) and Sn3 (1:64) scale size.
BTW, not to cause a ruckus, but 30" gauge really was pretty rare in the US. IIRC only 1% or less of US narrow gauge railroads used 30" gauge - making it rarer than 2' gauge. 3' was far and away the most common.