Check out the threads on the U Can Do 3D from Great Planes.

The plane needs at least a 90 size 2 cycle, but appears to be performing well. IMHO it is bigger than a 60, but not that much. Read the posts and decide for yourself.

BTW, yes, a 60 size airplane will 3D. I've seen 40 size airplanes perform some impressive 3D manuvers. But, it does have to be set up correctly and supposidly it is harder to do with the smaller planes.