i looked all over the place to find something for a slug 1 conversion. there isn't a database like there is with inserts, at least that i was able to find. i used this for mine,
http://www.tiptonium.com/videogames/reviews/neogeo/images/metalsluglabel.jpg
it is super ugly but better than just writing "metal slug" on an address label, which was plan B
supposedly, there are high quality art packs out there (insert, manual, label) for the more converted titles but i wasn't able to find them. most people hate that stuff (for good reason, people get ripped off) but it would be nice to have for those of us that don't want to A) swindle anybody in a sale and B) have an dumb looking cart to look at.