A friend assembled one of these and I recently saw it fly. He had a heck of a time with the CG. Had to add nearly 2 lbs. to the nose and using a 160. He originally mounted the tail wheel and rudder servo in the tail with a connecting rod to the tail wheel vs. a pull pull connection. Due to the CG issues he moved the servo forward in the fuse and covered the hole. He also had the mounting block come lose in one of the retracts. Ouch. Damage wasn't too bad, but he did discover that the glue appeared to be something like hot glue and not a good dose of epoxy. Then we noticed that as he taxied on a paved runway the weight in the nose caused the airplane to begin bouncing a little due to the weigh in the nose and the spring in the stock retracts. He had enough and has ordered Robart air retracts. The stock retracts had to go. I have the same in my WM P-51 and thinking about changing them as well. Just don't like the Egret leg appearance. and they sway terribly with any side load.

Here is a picture of his Zero on final approach. The airplane really looks great. It flies like a warbird with the 160. No extra power if needed or desired. Picking a gasser that would clear the cowling would probably be the best solution that would avoid having to use dead weight in the nose if you could get one big enough to add power to offset the weight.