OK, cool. I missed the CL version. Based on the wing area, I wouldn't use anything bigger than the 15 LA. Let me throw on a picture of my son's little ship. It's 31" span, about 275 square inches and one pound. It flies like mad on the LA 15. You could use more engine, but the increase in weight ruins the benefit a lot of times, on CL planes.

Do you have a URL for a source? I'd be interested in having more info on the Viper.