8" will be very very close. I just measured my cowl,if the heads could be placed as far towards the firewall as possible. Maby. But I did have an idea,if you mounted the engine on a 45 degree angle,you could by a little more room,not sure about exhaust. But it looks like at an angle,you might just have enough room. Or you could always make a small blister right wher the plugs hit the side. Not true to scale,but better than holes in the cowl. Gas powered sure would be cool in the plane. Mine has an OS 1.2 nitro. Good luck,let us know if you make the jump
mickey