If you want to built a gas powered Decathalon then you may want to look into the Dynaflite Decathalon. It has an 89" wing, is recommeded for a 25cc gas (the G26 would be great in it) and is available for $140 which is less than the Midwest. I've built the Midwest and way overpowered it with a FS 1.20 and a G-23or26 would never have fit under the cowl.

From what I've read about the Dynaflite, it's a pretty good kit to built too.