Instead of doing all that drilling you could try something like the "stock front swivel replacement with rail" found at
http://www.fulton-armory.com/MAParts.htm
I dont know if they ship to canada but it would make the bipod mounting easy to the rail and you could still use your sling. Or you could just get a USGI synthetic and remove the swivel and attach a bipod. There are instructions on how to do this in the battle riffles section i think. If you just drilled it yourself, like you were suggesting, it would likely hold as well i think...ive never seen it done.