There are 1000's of IH and CIH heads that will fit right on a 1680 and every one of them is better than any of the old top drive MF heads.
We had an 1144 MF head, thought it was a decent head until we got an 844 IH head. Didn't take long to decide the IH head was much better.
As for the value of the MF head, weigh it.