Okay, two answers to this one.
1) If you are going for accuracy given the time that the ship was launched, then the Baton Rouge was a contemporary and this ship was launched at/near the Four Year War. And it'd have been launched about 18 or so years before the Connie lauched, so should have an older hull and saucer type (like the Baton Rouge style saucer that I chose).
2) If you are going for matching the look of the old one, then we're looking at swapping out the Baton Rouge saucer for the Connie saucer.
But if we do that, I think I'll still put out the Baton Rouge style saucer'ed one as well, as I had a horrible idea to do to it.