[okawbow]

I've used Smooth-on epoxy to fill holes. It is a thickened epoxy adhesive I use to make archery bows. It has a pot life of at least 1 hour. You need a large syringe because it is thick. I used an old turkey injector. It also needs to be warm when you use it. You can buy it in pints, quarts, and gallon kits from bowmaking suppliers.

You might think about drilling the holes a little larger to get a clean, dry surface for the glue to adhere to.