I disagree with the gearbox being worth that alone.
Perhaps if it was a 63a or it was a 60 series that had been rebuilt, and you really,really wanted it, but $1600 for just for a used gearbox is a bit steep.

I think the offer of 1600 for the package is realistic. It offers a reasonable deal for both parties. Check out the ebay one posted on here atm. Plus its an overdrive which is much more desirable for a street car.

Much more than the offered price and you would have to seriously consider a ca conversion, or are you just trying to talk up the price because you have one to sell?