RE: 106" Aeronica
Just a guess, but I believe Bud Nosen made an Aeronca Champ in that size. It most likely would be 1/4 scale. An OS 120 single or twin should work nicely. If it is a Champ, the extra weight with the twin or a small gasser (Zenaoh G23/26) might be to your advantage due to the short nose moment.