Hey Jim, There isn't alot of room for a larger engine and weight wise the LA and Fox .40 are almost the same. My first plane was really the best flier. I tried to keep the wing skin adhesive light ( Dave Brown), built up wing tips and cowl chin, monokote finish and DB wheels. Almost 4.7 lbs. and 5 lbs is still good with the nice finish you have on yours! Scale loops will be great. The next one I build will have a built up tail feathers and use 1/8" balsa instead of the 3/16" stuff. Send us some pictures of in flight and let me know how it flies. Thanks! Richard