Meanwhile I have made templates of the cowling mounting hole pattern. I am trying to get each assembly identical so cowlings, engines and nacelles can be interchanged. I have modified the original design to accommodate my electric motors. More on the motors in my next update. I added a 3/16 circular plywood re-enforcement to the front of the cowling, This is the area you would normally cut out for a glow engine. I fiberglassed the inside and have bonded the cowl to the exhaust flaps. The assembly mounts to the nacelle with 4-40 machine screws. The screws go through the spacers into blind nuts. I need to get some cooling air into the cowling so that modification remains to be designed.

Any ideas? Suggestions appreciated. The picture shows the inside of the cowl.