If you are not sure about the new balancer, you might try putting a timing light on the motor and run it up to 2500 rpm where you feel the vibration and see if the balancer has an unusual motion or wobble.
When you mentioned pulley wobble, was just a bent pulley bolted to the balancer or an OEM style balancer with the belt grooves cast in it? If it is the OEM style balancer and it wobbled, you may have worn/damaged the snout of the crankshaft. This would allow your new balancer to move on the crank and cause a vibration.
For less serious items, make sure the bolt holding the balancer to the crank is tight and that the flexplate bolts are properly torqued. Another clue to a loose flexplate is when you shut the motor off, is there a tinny clunk when the motor stops?
Good luck on finding a simple solution.
