Nina,
Walkinshaw's _Annals of Southwestern Pennsylvania_ may have some information for you. It is searchable and there are some rosters there.
[
http://digital.library.pitt.edu/cgi-bin/t/text/text-idx?c=pi...]
The published Pennsylvania Archives, Colonial Series, may also have something useful, the gate way is here:
[
http://www.footnote.com/viewer.php?page=48491]
The George Washington Papers in the Library of Congress have some items on this period, but almost entirely on Virginians.
Good hunting,
Jade