I chatted with a fellow some time ago that used (I think) an RCS 1.40 gas with the C&H ignition. He seemed very happy with it, as it provided the weight needed, and power was appropriate for the airframe. I think a Zenoah 23/26 would be too large. I tried to find the thread with the details of the RCS 1.40 on this plane, but couldn't find it. As far as smoke on this plane, I think you would be asking for trouble. The plane finishes very tail heavy, and anything you add that isn't mounted on the firewall will be adding to the wing loading. I suggest trying to keep tail as light as possible, mount battery and throttle servo in front of firewall if you can, and finish in light weight covering to avoid heavy wing loading. Mount as much as you can as far forward as you can. I have this kit (still in box) with a YS .91 to power it. Another good engine choice for glow would be an old OS twin 1.20.