Going through and checking/updating card lists on munchkin.game is one of my long-term goals but the out of print games and expansions are at the very bottom of that list. There is, sadly, no easy way to do this; we used to have a way to export the card list from the database we use, but some update to the software along the way broke that script.
If fans want to send me cards lists to check/import, I'll certainly take a look and compare it with my archives. It won't save me MUCH time, because of the way I have to enter these lists on our site, but it will save me some. Those lists should be split by card type (Door, Treasure, etc.) and alphabetical within each type. Email them to
andrew@sjgames.com with the subject line "CARD LIST: [name of game]" (yes, all caps) so I can filter them appropriately.