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