It looks more like mahogany to me.
Cool old guitar but if it were mine, I replace that metal bridge. I love these small guitars.
Supertone's did come with Koa B&S, laminated construction. Your photo does seem to have the golden brown color of Koa but the grain looks Mahogany like. Removing "poured in" glue is not an easy task and very time consuming. If it's tightbond or white glue, soaking with water for several days will soften it. Can you tell what kind of glue you're dealing with?
Looks like white glue. Was thinking of hitting it with the steam needle used for getting necks off. If I could pull the strips free, then work on the glue. Back and sides appear solid, as the grain matches inside.
More than likely Mahogany then. If it's white glue, I've had success with hot wet paper towels applied just on the glue if possible. The glue mostly peeled off with my angled scribe point.
noa.....that's much closer to mahog