Don't use an expoxy bed, you will NEVER hide the repair. Cut a wood shim. When cutting the shim, try to match up the curl as best you can.
When finishing, get you a couple VERY small size art brushes, the smallest you can get at an art supply store. "Paint" the area darker with darker stains and fade the color the farther away from the fix. Sort of like having a spot on the fender of you car painted. Stain you stock prior to doing this. That area fo the rifle can be dark. Use Elmer's stainable wood glue. I have tested this stuff out and it is strong enough to make that fix. Don't use epoxy bedding. You will never hide the epoxy glue line.
If you can get some plain maple, without curl, use that. Then you can just paint your curl where you want it. You can also use some paint pigment mixed in your finish oil and put it one only in that area and fade out.
Glue in the shim now and continue building the rifle. Play with making repairs with scrap pieces of wood and finishing it. WHen you feel you have enough practice, do it to you rifle.
All builders make mistakes sometimes. The thing that sets the good builders apart is being able to hid the mistakes
Brian