Mine balances with the 2 A123 flight packs about 2 cutouts aft of the tube in the 1st "bay" behind that is the reciever and behind that the 2 rudder servos.
Ignition was mounted behind motor box and 1 A123 next to the tank.
I have a CF spinner so you would need to allow for that.
The flight packs are easily moved forward or back, Ist flight I put them a little forward and then after that moved them back 3" once I knew how it flew/landed so Im on the aft of the tube now.
Ignition pack is now back against the tube since I took these
You can see 1st flight reciever pack site in one photo, and the one with them even is the current place.