The CDI kit shown here can be used on ZA50's and E50 puch motors. Most of the time they can be bolted in directly without modification.
For the E50 it is installed as shown below. You will have to remove the brown ground wire from the back and put it on the front. At the same time you should swap the screws on that coil, as the longer bolt interferes with the case if left on the left side.
Some kits required enlarging the adjustment slots in the plate in order to get full advance. Others have bolted with no issue. If you find that your timing is retarded still with the plate at full advance, you likely need to break out the dremel. Moving the pickup to the other side causes it to be advanced too far.
For the ZA50 the plate is installed as below. It should bolt right on, no reported need for modifications.