Clean metal with the right heat and lots of the shielding gas shouldn't have any porousity. Exceptions are crappy metal like a BAR receiver, which is some kind of cast aluminum/steel mixture I think.
If I were you I would go for the fill and refinish as well. And leave the LB butt on it and mail me the sniper butt as partial payment for the great advise.
I picked up a Brit sniper on the weekend....pretty good condition except the butt does not have the S51 and the cheekrest has a slight crack in it. Has a real great transit chest and an excellent scope can with strap.
Partial payment...hehehe
Was the Brit sniper reasonable or the usual astronomical?
How much would be reasonable for that Ottawa gunsmith to charge to disappear the holes?