I would stick with a cam that's specific for a 351 rather than a 5.0 piece. A 351 with it's longer stroke requires different valve timing than a 5.0 for max efficiency. Sometime compare the specs for Ebrock Performer RPM cams for a 302 and a 351. Same lift and duration but opening and closing points, lobe separation, intake centerline are all different to take advantage of the 351s longer stroke.
70 Maverick Grabber, 5.0 (Performer RPM 2.02/1.6 heads, RPM intake, Comp XE266HR roller cam, FiTech EFI, EDIS/MegaJolt ignition, long headers), T5Z w/Steeda TriAx shifter, 9" "N" case Trac Loc w/3.89:1, 31 spline axles.