The balance point will not change as a percentage of wing cord or away from scaled plans balance point UNLESS you severely alter the wing profile! In scaling up an FT plan the balance point will be as indicated upon the scaled up plans.
It also does not change if you build it out of balsa, Plywood, XPS foam or any other possible material as the balance point is a result of the lift generated by the air moving around the object so its material is irrelevant.
The only thing that really changes is that as you increase the size the wings actually become more efficient.
Have fun!