Hi Jim
I think I used 6" CG I will check. I bought this plane with some parts (not assembled)motor, retracts, battery, from a friend. I moved the motor as far forward as I could by having a shorter prop hub made. That moved the motor about a 1". I put a battery tray above the motor with a very large battery. besides the shorter prop hub and the large battery I had to ad about 6 oz. to balance. The retracts I got with the plane, I think they are Robart spring down, with machined partial strut and bent to fit the wells, also robart struts came with the parts. The Robostrut are for a 14lb plane but I am going to put in bigger springs/spacers and give them a try, with the solid machined partial the robostruts should be fine.
I will take some pictures and post.
Clay