Aww, Marco is a cutie! Definitely take Jackson with you. I hope it works out! I'd love a second dog, and Levi would love a playmate. It's just not the right time for me.
I don't think it's rude to talk health contract with the previous owner. Type something up. Get her to go over all of Marco's vet records with you and don't be afraid to question anything.
Good luck!
