Have my Golberg Cub that I built in 1993 its Solartex covered and powered by an ASP (Magnum 61) four stroke which is plenty of pwer for this model it flies in a scale like manner at around quarter throttle. Mine is a full winged version and i too built over plans and encountered the non-fitting problem around the cabin top, until this post I thought I'd built it wrong!I simply cut the end ribs off made half ribs and laminated them to the outside of the cut ribs which gave me the necessary clearance. Only other mods were to make the undercarriage a bit more scale looking and to attach the wing struts to the fuslage with ball joints and a small brass plate and to use cut down control horns and cdlevces at the wing ends to make rigging at the field a two minute job. Definitely needs coordinated rudder aileron turns but is still an absolute treat to fly on a still day