You're welcome krisright.
His naturalization intent and petition should provide you with a place of birth. Hopefully you will also be able to find his arrival manifest.
I hear that the US German churches kept precise records on their congregration so hope you will get the documentation.
The surnames that you say he changed it to seemed Lithuanian to me as that is why I suggested Lithuania.
Is it a bit unusual for a German to changed spelling of his name to completely not resembling the original spelling?www.genealogienetz.de/reg