2holer
I've never used cyanoacrylate as a sealer for the head of the stock. Just a SWAG but based on my experience using cyanoacrylate for other things I'm thinking yow will get better penetration & less worry about surface build up with the thinned acraglass or other epoxy. On sound wood & good inletting you dont want any build up & when done really shouldn't look any different except maybe a little glossier & any pores mostly filled.
Steven Dodd Hughes touches on this in one of his books (Double Guns & Custom Gunsmithing I think) & if I remember correctly soaks up the inletting cuts & head of the stock with thinned poly finish such as Permalyn. Done correctly, several different methods will work here & IMOP are better than leaving the wood unsealed. Sealing against oil migration will for sure prolong the life of the stock & properly sealing it can't make it any weaker.
