You must own all rights to the song to post per PG Music rules.

Per US law if the song is truly in the public domain then you may create an original interpretation of it and own ALL rights to your version - the same as if you wrote it. You may not use another artist’s version. The US has very strict copyright laws. Each year per recent law songs enter into the PD that are 75 years old. A Google search will list the songs that enter each year. If they were recorded and/or formally published less than 75 years ago they are not in the US PD. Per the above we have had several PD songs licensed and we receive all revenue from them. Note that there is a lot of bad info on the net about this and you have to dig a bit deep to ferret out the actual protocols.
Hope this is of some help.


Bud