Here is the [link=http://shop.traplet.com/product.aspx?c=584]web site[/link] for the plan . The plan makes a 2 seat trainer that was powered by a 5 cyl Kinner radial. The crop duster variant 9 ( ther was one that flew in the '50's ) used a 7 cyl Continental. There is not much on the web- believe me I've looked to make the crop duster. But here is what I've found
http://www.aerofiles.com/_ga.html
http://www.flickr.com/photos/34076827@N00/4730900942/

I have some more somewhere but see what you can dig up on the other side of the pond.