Nice engine is that a custom muffler ? I plan on useing a magnum 91 4 stroke with a EDSON universal motor mount , its a outstanding mount that allows for easy forward and aft movement of the engine along the predrilled rails.

As far as the air intake , there is a couple of problems , even if you solve the one the bottom cowl is still to flat as opposed to the upward round found on the real one .
I thought about scroling out a soft upside down Y in hard wood, coating with expoxy and putting it in place . Its a lot of work and I dont know if it woudl work and hold under vibration . I cant wait to get more done but I have been working on my GWS A10 and trying to get some flying in .

Last idea, cut a small line in the top and two small lines in the side in the positions to hold an upside dwon Y . Clear out the existing form and cut you new form out of thick plastic , sliding them into the slots that are cut , slide the bottom one in first (it woudl look like a frown at this point , then slide the top piece in the top slot and the slot cut in the bottom U -confusing but I can draw in you need it