This mod is not for the faint of heart. The wires in the cables weren't color matched to Nintendo standard (red = power, white = ground, et al) and the cables didn't match each other. So, everything has to get buzzed out and labelled.
The JST connectors inside the controllers are impossible to remove cleanly. Should have just cut off a one inch pig tail and spliced to that.
Anyway, all said and done, everything works and it's easy to tuck the cables inside the case and seal it all back up. Couple odd notes - the system takes about five seconds to recognize when you've hot swapped a controller. If you plug the controller with start and select into player 2, they're functional. Player 2 cannot control the system menus.
I did three feet of length on the female ends connected to the console.