I've heard that one person is using a LittleScreamers Purple Peril on an APC 7 inch prop but I'm using the Hobby Lobby Esskay 400XT on a 9x7 APC prop. My setup is pushing about 130 watts. I was going to use my Park 400 on it but I had not tried a 400xt so I decided to put that on the plane. The e-flite stick mount works great on this plane by the way. I tried the GWS one but it puts the motor to low. The e-flite one puts the motor dead smack in the middle of the cowl.
My plane came in at around 19 ounces RTF and balanced. If you can get it lighter I would recommend you do so. The manual states 17 ounces and I probably could have hit that if I had used lighter servos and a lighter battery. The Park400 should help you balance it out. The 400xt is pretty light and I had to add some dead weight.
Oh and feel free to add your build to the build thread if you want. There is almost 0 information on this plane out there so the more info the better.