icarus46

I'm considering this kit and want to use a 15cc RCGF gas in it. I will definately not be flying full power with it. I dont want to go glow power but considered electric also but really like the gas engine idea a little better. From the firewall to the cowl it is 3.5" and the gas is 5.375' from the stand off mounts to the prop hub so that means I either move the firewall back or not use the mount stand offs. If I didn't use the standoffs and mounted the 15cc directly to the firewall would it vibrate the plane to pieces?
Heres 2 pics, one for the motor and the other is the specs on the plane. Thanks for your time and help.