Layout the timber in a rectangular shape, so there's an 800mm piece at the top, butt join a 655mm length of timber on each side, and then a 710mm length of timber at the bottom. Clamp the timber together. Drill a 5mm pilot hole and countersink. Then glue and screw into place with the 100mm bugle screws. Screw from the top of the 800mm into the 655mm lengths. Screw from the side of the 655mm lengths into the 710mm. Leave the glue to dry.