have you seen or heard of the rib "vertical bracket" mod?
it was done on 2-seaters and Elite's - a 90 bracket between the spar web and each rib. it involved putting a U-channel on the flatside of each rib sparcap (between the rib and sparweb, so you have to remove the rib to do it), and then riveting an L bracket (about 5" wide) from the spar web to the U-channel.
it prevents the rib from moving up and down, as the flex of the gussets are the only thing holding the nose of the rib in place.
just a thought, since you've got it all open............ only another 300 or so rivets to remove and replace
Tyler