"My GB5 and Sparey 5cc both very happy on 13" and 14" fans-but these are big sideports with Mills like handling"

What are these engines and where do you get them? I'm interested in diesels for scale models of WWI rotary engine types. I have a PAW 40 that I've installed in a VK Nieuport. Problem is that PAWs are too darned long--they don't fit very well under the hood. I'd love to find a Mills-like large diesel.

Jim