Missing town - Zamosc

I am trying to find out ways to track my grandfathers ancestry. On his papers coming to Australia, it says he was born in between the world wars (1924) in the town of Zamosc in Wilno province. From my knowledge at this time this was apart of Poland at the time but now is either part of Lithuania or Belarus. Looking at the maps now it seems to have either been renamed or doesnt exist. Has anyone have any idea what the town is near or what it might have be renamed to? It's not the town of Zamosc in the south east of present day Poland.

Also would it be better to track other ancestors through the present day countries of Lithuania or Belarus, which ever country he was born in? Or would Poland have those records?

this will give you your answer: jewishgen.org/Communities/LocTown.asp

there are a couple of possible locations.

enter the town name... press search... scroll down.