RE: Goldberg Ultimate 10-300 build
I have had similar problems with various manufacturers. I find the simplest and quickest way is to cut new notches (or trim the ribs). They aren't really structural but just an aid to assit during construction. It doesn't matter if the notches are wider but do really try to make them the correct depth. Put a nice small fillet of glue either side once you remove the wing from the board.
Any other suggestions out there?