I was thinking about buying the Elderbrock Performer or S&S big bore kit with gear driven cams but are these kits worth it or would it be better to just buy my parts seperate like upgrading my cams from the 203's,Manley valves,JE pistons,New heads and new jugs?

Usually with the kits, they offer a slight discounts with parts. If it's a shop putting it together and you want something specific or a little change, I'm sure they'd work with you.