Could you add these resources later?
http://forums.civfanatics.com/downloads.php?do=file&id=10461
Potato should Definitely be in america, also rubber and timber are appropriate too. I don't know how necessary the amber is. And America should definitely have a gold resouce, where do the natives get their shiny coins?
Just a suggestion though.
Use of rubber was at the very tail end of the C4C scenario, so it's not really "historically correct". Potatoes are an interesting addition to then South American regions though.
Re: This mod. It's a bit annoying only being able to fit one 350gp treasure on a galleon. Why not have it so that each slot can contain 250gp or 350? That way you can squeeze a few smaller treasures in or have one large one.