Most kit manufactuers in the earlier days use balsa that was harder than most of what you see now days....The Faster the tree grows the softer the wood will be and the grain pattern will be wider. It has to do (in most cases) with the growing season. Pacific Coast Maple is softer than Maple grown in the east due a more moderate climate, and longer growing season. Most kit manufactuers substitute Basswood for Spruce because it is becoming rare and expensive. You can buy spruce here
http://www.aircraftspruce.com/catalo...s/capstrip.php, and forget the basswood all together. And yes, Balsa is a Hardwood (has to do with its leaves) Maple does not glue as well as some other hardwoods due to it's density, there is little open grain to allow for bite. Maple's strength is overkill. I think you could use Poplar or even Mahogany where it calls for maple (usually landing gear blocks etc.), and both glue better than Maple.