Guillows Cessna
Just another thought - I was in my Hobby Store and saw that they had a very nice Guillows kit for a 36" span Cessna ?Skymaster. Might be a bit small for adaptation to R/C with a 400 but perhaps worth a look. You'd have to build the kit a bit lighter than it would be stock, and if the wing-loading with a 400 looks too high, it might work for a 300 or small brushless (Razor). I reckon the wing area is probably about 1.5sq.ft so you wouldn't want to have a ready-to-fly weight of more than 12-15oz [i.e. 8-10oz/sq.ft wing-loading].
Cheers, Phil