The thing you have to be aware of is that "water based stains" sold for woodworking purposes many times have a latex base because they want them to be water proof or resistant. This will seal the pores of the wood and inhibit the epoxy adhesion. Analin dye is a good way to go or buy artist water color and make your own with water. Keep it thin. The raised grain will actually improve your epoxy adhesion. As always experiment on some scraps.