One thing to take into consideration is which version, large tank or small tank. When the 1/2A Texaco event started, they used the larger tank, like the Golden Bee and Black Widow stunt tanks. The guys started to figure out how to make a Cox .049 run almost the full 15 minute max on that large tank of fuel (8 cc? ) Then they changed the rules to make the smaller tank mandatory. Guys that use them for competition need the small tank. I'm of the opinion that there isn't a lot of collector value to the engine, aand anybody that wants it will probably use it in a Texaco model.
Type at you later,
Dan McEntee