SV-11 is for 40/51 big block size engine and pipe combo. SV-22 is for 61/65 big block engine and pipe combo. Per Randy Smith. I had this same question for him 2 weeks ago and called him. The fuselage on the SV-22 is larger for the bigger pipe and the tail is enlarged to control the larger props. I think that is what he told me in a nutshell. There is no kit for the SV-22 only rib sets, but there is a kit for the SV-11. He list the Katana SV-23 for the 75 size engine.
Edit: To put in big block. The SV-11 is too big for the U.L. Merlin 40 per Randy.