Regarding early tax records for Pennsylvania, Franklin County taxes would be listed with the Cumberland County records since it was not established as a separate county until 1784. However, the place for you to do your research would be the published Pennsylvania Archive series. This is a series of about 130 volumes (some three inches thick) that were published in the late 1800s, and there are tax lists for all of the early Pennsylvania counties. The archives also cover many other topics including about a dozen volumes listing all of the Revolutionary War veterans by name and many by military company or regiment. All major libraries in PA would have this series on the shelves. And I am certain that many of the large Maryland libraries would also have this set of books.