I cut the Horizontal stab open to install a Hitec HS-125 MG servo. Made a hatch and itis ready for assembly.

The wood dowels supplied are less than 5.5 mm in diameter a SLOPPY fit for 6 mm holes.
A trip to the Orange store got 1/4" dowel to sand down to a good fit a 6mm.

Rudders will be added to the fin panels.
Servos will be place in the original elevator pockets.

I will fly the plane using Elevons mixing, JR sport 125 mg servos supply more torque than needed.
My Futaba 9CA P-mix elevator to an aux channel to drive the real elevator.

Most delta wings need plenty of elevator throw.
With this set up I will hve plenty of control authority.