http://www.pennpilot.psu.edu/ has posted 1967 aerials, fwiw. Also, as an aside, Pittsburgh City Planning has aerials from 1962, 1966, 1976, 1982 and later, $5 for a paper copy of a plat (and the plats are the same as the ones in the Pitt Digital Archives Pittsburgh maps, and the paper copies at full scale are about the same size)