Great question and I apologize if my research efforts to develop these have jacked the thread. Once I have everything figured out I will create a separate thread complete with pictures and explanation, but I thought this thread would be best to update people on my progress.
I believe you are referring to the 240sx kit that uses the Z33, 350z track rotors with the Z32 calipers. That is NOT I'm using.
These brackets are similar to the 4X4 kit, except I'm not sure if a spacer will be necessary. With the current rotor I'm testing conceivably you COULD have it drilled for 5 lug applications.
Because of the increased size of the rotor and the larger caliper than the 4x4 kit I highly doubt it will weigh less, but once it's assembled I will weigh it all as well.
Hope this answers your questions, As soon as I get the rotors I will update you.