The electronics will fit, it will just be a bit harder to do. Here is a picture of the kit from the kictarter video:
The wires going from battery end to the LED look long enough that you can push them all the way through the body, connect them to the LED, and then slide the LED into the emitter. However, with how short the wires coming from the switch are, you may have to fully disassemble the saber to be able to reach the connector.
TL;DR: Yes they will fit, but will take some finesse to install them.