Stalwart Unity is more of a personal preference than anything else, because I like group-hug-type decks that look to pillow fort, draw cards, and then hopefully win the game eventually
Griselbrand If the other two are on the safer side, Avacyn Restored
I have read a related post in this site but it doesn't clarify if this can be done or not because for one side it says: If the card is legal then the card has black or white borders and then it says: Artistic modifications are acceptable in sanctioned tournaments, provided that the modifications do not make the card art unrecognizable, contain substantial strategic advice, or contain offensive images
Also interesting to me are the story changes these remakes make
this type of repeated creature generation works nicely in a sacrifice deck, where you can let those Snails serve a higher cause by making mana or being used for spells
I also agree with what @pfm said, the focus on the older cert number would likely be the best bet of making sure the stamp is rather legit