If you go with foam core wings, you really don't need plans. *After building a dozen or so kits, you'll already know what should work. *I built a fairly large Yak 54 without plans at all, just, yeah, that looks about right. *If you want to use a built up wing, I'd just enlarge a Sig Fazer 50% larger. *To be honest my Yak 54 flies as well as any kit I've assembled.