The engine mount was already assembled from another build that didn't get finished.
The assembled mount is nothing out of the ordinary and should work fine in this model.
I wanted the root edges of the wings to be square.
My straightedge was taped down and one wing was glued up on each side.
Enlarge the picture and you can see the front fairings don't quite match up to the larger wing piece.
Pinning from the outside edges puts pressure towards the center pushing the joints together. Don't press the pins against the balsa too hard, they can leave small notches in the edges. Pin with just enough pressure to keep the joints tight while the glue dries.
You can't use a book on top of the pins so two glue bottles were set down on the glue joints.