Heavier wheels would probably dictate heavier springs but I don't know if the OEM sport wheels are that much heavier so it's hard to say. Same for shocks.
The problem is you don't really know how those stock parts will perform with your non-stock wheels. Ford goes to a lot of trouble to match the OEM setups so you get a consistent feel whether you have 18s, 19s, 20s or 22s. Just changing one piece of the puzzle can yield bad results.