Primary aka the short shoe goes in front.
Secondary aka the long shoe goes in rear.
The park brake will work fine if you can jam all the springs, cable, bar, and adjuster in there.
What will be effected most is braking.
Have you ever noticed that drum brakes don't seem to stop as well when going in reverse as they do going forward?
That is all to do with the position of the shoes.
The secondary shoe does damn near all the "stopping".
Getting them mixed up on the rear axle will effect braking distance and some pull one way or another.
Getting them mixed up on the front axle will effect pulling one way or another.
It will effect braking distance but it is not as noticeable from the ditch %)