I searched the Irish Family History Foundation's database. It contains 11,500,000 surviving rcds for abt 60% of Irish counties.
For a Henry Crawford and Mary Montgomery marriage in 1874, I found matching M rcds for the two in the parish of Drumcree, Co. Armagh. These rcds are likely for your ancestors. There were NO M rcds for these names in Lurgan.
Google the Foundation's name to lead you to this database. Pls post your search results to my genforum msg.