I'm guessing that the stocks used on the 788 are Birch...maybe maple but I think birch....and the good news is that while they need to be stained for a dark finish, the pores of the wood are small compared to walnut.

You can get stains and finishes from any hardware store.....after all the 788 isn't a custom classic!! You also can get various stains and a spray on urethane (custom oil from Chem-Pak in satin or gloss) from Brownells. I'm very happy with this product.....

Make sure the stain is thoroughly dry before trying to apply a finish.