If he tail mounts all the rudder and elevator servos, moves the throttle servo to the middle of the plane, places the flight battery as far back as he can, runs the lightest ignition batter he can find, and doesn't try to beef up the firewall, it can work.

The plane will still be on the heavy side, and will not want to slow down enough to land because of the residual thrust with the bigger prop and the 4.2, but it will work. Perhaps not as well as it could