The Northstar plan was published by RCM (issue 3-86) as plan #pl-960

You could build it from the plan, or a kit made by Balsa USA

When you build it, I too recommend improving the elevator linkage like the others said.
I would also strengthen the join between the engine pod and fin, by filling the corner with balsa triangle and covering with light glasscloth/epoxy from the pod sides right down to the fuselage under the wing.

Another useful mod is to install two aileron servos and connect them as elevons, using a Tx mixer (as well as the usual elevator).