Lots of engines would fly a 1/4 scale WWI model just fine. But my opinion, only the Seidel looks scale enough to consider not covering it with a dummy engine. The Saito 3-cylinder 170 is a nicely made engine and beautiful in its own way, but I wouldn't want it poking out the front of my scale model. The Seidel still isn't quite right (looking a bit more like a Pratt and Whitney) but it's the only one of the radials that would look right in WWI cowl.

http://www.horizonhobby.com/Products...odID=SAIE170R3