I have the busa 1/4 scale J3 kit, and bought the L4 plans (from busa). I traced all the parts in the kit and have a fully framed up J3 and L4 greenhouse version. The L4 upper cockpit frame where the wings mount are not as strong as the J3 varient but is ok as long as you dont get crazy with the menuvers. I was originally going to power them with OS 1.20 4-strokes but have since change my mind and will be going with 20cc gas 2-strokes. I prefer the sound of the 4-strokes but glow fuel costs convinced me to convert to gas on future builds. Its not a hard build, very straight forward. HOWEVER, the ailerons are not scale. Not a big problem if you are a builder. Its easy to modify the ailerons to the scale bottom hinge location. The kit is top hinged for the ailerons. Mine will be using a pull-pull setup for the ailerons. The elevator is not in the scale location either but that too it not a big deal to modify. Just look at some accurate 3-views. I would highly recommend you install the rear float mounting plate in the fuse when you build. You never know if you want to put floats on.

Nothing looks finer than a cub side slippin down to the runway center line.
Edwin