I agree, that looks like a Goldberg Anniversary Cub. That kit is still available from Tower Hobbies, and is now sold under the "Great Planes Goldberg Anniversary Cub" name. A product manual can be printed off the Tower site on the page for this model, however the C/G information in the instructions tell you to "refer to the C/G range shown on the plans". You don't have the plans so use the 25-35% of the MAC method to find the C/G range. Accurately remeasure the wing cord (you said yours was 11", but mine 10 3/4" so be sure of your measurement) and multiply that number by .25 (25%) and that is the start of the range and then multiply the cord by .35 (35%) and that is the end of the range that the plane will fly in. I would advise you to start off close to the 25% area, no more than 29%. If your wing cord measures 10 3/4" as mine does then 25% of the MAC is 2.68" and 29% of the MAC is 3.11". However if your wing cord is actually 11" as you stated then 25% is 2.75" and 29% is 3.19". In any case I think 4" back from the leading edge is too far. Yes I know the spar is there but "so what". Measure the wing cord and multiply it out for your wing cord size. Hope this helps.