The clutches rotate counter clockwise.......you bolt one on so the shoe trails behind it to the right, the other shoe can only go on the same way. The shoe trails behind the bolt.....it's simple.
If you need an illustration I can dig one up for you.
OK, look closely at the picture on the right. That is the left side of the engine with the clutch installed and exposed. It spins counter clockwise as we're facing it here.
Look at the bolt on top holding down one shoe and notice how the rest of the shoe trails to the right. That's the way they are to be installed, even though they will still engage if you mount them backwards the opposite way.