I also agree as swapping cams is a costly endeavor and timely. The cam will not really do much for you plus the stock valve springs will not enjoy the extra lift.
Stock heads are very big restrictions as well as the stock intake manifold which is even bigger. These stock 5.0 are like little diesels and make power down low and run outta steam at 4.5k rpm.
1989 Sonic Blue Mustang LX Coupe, 349 ci, TW heads, TFS Track Heat intake, 75mm Accufab TB, 80mm ProM, 30 lb inj., Jay Allen cam, TKO, 3.73, 31 spline w/ TruTrac, MAC 1-5/8" LT headers w/ h-pipe, 2-1/2 flowmaster, electric fan oh and a Moates QH
392 rwhp 424 rwtq....Mustang Dyno
"There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." -Will Rogers-