I've shipped a dozen or so pianos internationally.  The cheapest
method is with a consolidator who puts numerous items in a container.
You should get the piano crated.  Otherwise, you can get a 20-foot
container of your own and move other stuff, too.

Your main concern will be ivory key tops.  The USA does not allow
importation of ivory products under 100 years of age.  You will need
the correct "CITES" paperwork proving age.  Hopefully, the Knabe
Ampico has plastic key tops.  You can also save the hassle and remove
the ivory.

You'll need a Customs Broker at both ends, unless you are a
do-it-yourselfer (like me).  Costs include transport to crater,
crating, transport to shipper, loading on ship, unloading, Customs
fees, transport to destination.

Philip Jamison