I wouldn't do this.

plywood stands better through stress than balsa.
stress = force / area
means you need much more balsa to stand the same amount of stress as plywood.

who ever designed this airplane didnt choose balsa for a reason.

how many ounces do you think you are gonna win?
while you are risking the whole airplane.

cant you just put a bigger motor?

I dont know the global raven 60