Since my recent posting on this topic, i've heard >from a few
'genners...and learned of a book,
The Old Jewish Cemeteries of Newark
by Alice Perkins Gould
This book is available through Avotaynu.
http://www.avotaynu.com/books/Newark.htm

One genner wrote that the author of the book had a map of the cemetery
and database of the plot numbers of its occupants, and by contacting
her he was able to find the graves of his grandparents.

Happy Hunting!
Phyllis Kramer, VP, Education, www.JewishGen.org/education