Carol, your best bet would be to request a church baptismal record of the ancestors' children. Another thing you can try to locate is Anton's first arrival manifest to America. His naturalization intent & petition should also have a precise place of birth.
Dawidextis, AntonGadveim, Russia2818771905 [going to brother.i.l. Kasimir STANKUS Pittsburg, PA Box 1? Morgan Allegh] Location Gadveim is not written legibly to try to decipher it.
We know that the location Spestven is in Kowno gubernia and that is where we need to find it but the spelling is not precise. No other person came thru from that location.