Sal Trapani would often employ ghost pencilers, or use swipes. It's not clear what he did in this story. Merlin Haas identified the artist. Alan Hutchinson, Marc Svensson, and Edgar Loftin suggest Steve Ditko might have ghost penciled some of the work, but from information culled by Robin Snyder, Ditko was not involved. Al Williamson inks per original indexer. Trapani inks per Merlin Haas, Bob Bailey and Ramon Schenk.
From Gene Reed - 9/3/2016 - Not sure about the inks, but the layouts and pencils look a lot like John Severin, especially the middle tiers of pages 2, 3, and 4. Ted Galindo may have had a hand in some of the panels as well.