Paul,
 
You wrote that you were concerned that the emergency queen might not be
mated well. If that's the concern and you are going to replace her in
your original hive, what makes her any better in the split. If it were
me I would order a second queen to make the split with. You don't what a
small split struggling along trying to get started with a queen that
might end up a drone layer right away. Just my opinion. Good luck with
whatever you decide.