Long Live the Power: Before all your mods are installed pull the engine apart and send it off here: http://www.swaintech.com/ Power will be improved about 15% and the engine will run forever. Get the piston crowns, valve heads, combustion chambers and exhaust ports ceramic insulated and have the hard teflon coating applied to the piston skirts. After all, you want all that combustion heat to push down on the piston, not heat up the water jacket for a comfy ride in chilly weather.
Get new heads. EdleBrock has a pretty good selection. Your 5.0 is the almost the same as a mustang right? If it is, I'd look at sone mustang forums.