Quite often the best place to find where someone was from is to start with where they died. I suggest getting Lillian's death certificate and obituary. Both should have her parents' names and her obit may have her exact birthplace and surviving siblings which can be a BIG help. If you know where they married then get their marriage record. If you know what church they were members of or where they are buried check with each to see what may be in their records on them.
Check with the Johnstown Area Genealogical and Historical Society to see if they can help you also the Cambria County Genealogical Society and the Cambria County Historical Society. You might also try the Afro-American Historical and Genealogical Society - Pittsburgh Chapter. I believe they cover the western half of Pennsylvania.
Although Lillian is listed with Joseph in the 1940 census on Joe's WWII draft registration card he lists Mrs Lillian Shannon as someone who would always know how to get ahold of him. Did Lillian remarry?
One researcher posted on Ancestry that Lillian's first name was Amanda. Why I don't know. They have her listed as dying in 1974.