As long as your new dog has his Parvo shots, he'll be fine. It sounds like you've done everything you should once you realized what was going on, which is a lot more than most would have.
If you are worried, take your new dog to the family vet immediately after picking him up (no stops at home or pet stores), and have them check the dog over, give him any shots he's missing, etc. Most vets should be willing to make an appointment ahead of time for the day you bring him home if you explain the situation.
Avalon - Male Butterfly Double-Tail Halfmoon, Pink/Cellophane
Camelot - Male Marble Double-Tail Halfmoon, Black/White
Merlin - Male Delta, Steel Blue/Green