i guess it depends on how much u plan to move over, but chances are buying a wrecked EB/ED in good condition shouldn't be too hard.
there are plenty of wrecked cars out there
You'd see a performance difference as your still basically using the same body (weight) and will have a car with about 20 or so extra kw's
look for one in maybe the same kinda colour as urs or something as the doors off a later model would be better to put on yours due to speaker holes and stuff. not sure about smartlock? converting engine/trans etc etc is a lot to do but a good project none the less :D
good luck to ya