i thought it would be easier if the front trunnion was out of the way,.. once the rear fit correctly into the trunnion i put the stock on and folded it to see where the hook would need to go,...i used a marker to make the marks where i would have to cut,..and used the hole in the trunnion as kind of a drill guide for the pin hole in the reciver,.. then filed it out until it was big enough for the pin.
of course i had the luxery to remove the trunnion and other parts at will because nothing had been rivited,... only locked in place with a C clamp
your mileage may vary
the other way is get the blueprint off pookies site and go by that if the trunnion is installed.
a little advice though,...when you go to put the spring in the rear trunnion,...do it with the rifle inside of a huge zip lok bag,...the first few times i tried it the spring flew out like a bat outta hell
also that pin hook and spring up front will piss you off so bad you will want to smash the kit into little pieces,...take your time,.. you will win eventually.