I have seen posts on here about the difficulty of finding harmonic balancers. Stevens Specialty Auto Parts has new balancers for Chevrolet and Ford sixes. Their phone number is 1-800-443-2673.
They said they have balancers for 250s abd 292s. They quoted me a price for a 1978-83 250 for $59.00. Seems pretty reasonble. Their ad doesn't say where they are, just their phone #. Hope this a help to someone. Joe