I don't recall..they are possibly a little bit heavier than a Cox .049. Any plane I've had a VA or Cox, or Norvel engine in has taken a Cyclon or Fora swap without too much trouble. The important thing is to have a stout 1/4" ply firewall that is fiberglassed in to the fuselage real good.
The power is so high that there's no point in being anal about weight. Just keep the wing loading to a point where launches and landings are predictable.
The lower limit for wing area with a 11 oz model is about 120 sq inches. It's really important to find light 1/4" thick balsa for the wing plank...but don't buy "punky" wood that is so light it has no grain.