303Enfield870Remmy

I found this YouTube video which seems to answer my post. I was confused by the action bridge. I hope this thread can help someone in the future.

Hey all, Hoping someone can help identify some parts on my sporterized .303 Enfield. My plan is to equip with an ATI Monte Carlo stock, scope mount, and a 3-9x 40 scope. I am not in close proximity to a gun smith, and with two little ones, taking the firearm to the local gun shop for some advice doesn't work for the family. I am wondering where the scope base will tap into on my No4 MK2 Lee Enfield. I have attached pictures in hopes to get answers on the screw holes situated on the action and barrel. http://imgur.com/a/SrAub