I don't remember which set goes to the front or rear. When I take mine apart, I set everything in order into the inverted valve cover.
I am surprised that they will interchange. If you set them in place, can you tell where they're supposed to go? Also, another hint might be the notches in the shafts that allow you to reach the head bolts with an extension. If you set them in place and look at those notches to see if they align with the head bolts, this might help you to figure it out.