pceagon,
You've got about 11 1/2" inside the cowl, maybe a little less depending on where the center of the cylinders end up. I have mine almost completed.
I have a question for Phillco or anyone else who has flown this plane. Where did the CG end up on the first flight and did you adjust it later? I can't get mine at the recommended location without adding a lot of weight to the nose. With a ZDZ80, all my batteries up front, throttle servo and ignition on the motor box and pull- pull on the rudder the CG is only one inch forward of the wing tube center. Tom from Wildhare has told me this will probably be OK, I'd just like to hear from anyone who has checked their's.