What would happen if you replaced the change lever with one from a L2A1? ............. nothing much will happen.

 

You will be able to rotate it to Repetition and it will shoot Semi

 

You will be able to rotate it to Automatic and it will fire ....... on Semi only

 

You still have to replace/alter another component to enable the rifle fire on automatic using the L2A1 change lever.

 

Now for the legal crap, this in no way condones the use of parts that may in some countries/states etc, be illegal to own or use yada, yada ya.