Suzuki 2 Strokes

Hi,
I have a GT750 A-engine and want to use the simple neutral switch only from the early J-models without gear indicatir since the gear indicator switch is broken and leaking and I will not have a gear display anyhow (its for my BIMOTA replica).
What exactly is the difference between the early and later gear selector drums? Is it just a threaded hole on the early ones instead of the slot? How could I modify it to mount the simple neutral switch?

Picture shows my drum:

It's not just the thread, though that is important. A J shaft is shorter and a different nose shape to fit under the phenolic resin case.

A later model with the gear indicator also contains a neutral switch and blue wire. I would use a stock later model switch and delete the wires you don't need. Just keep the blue (neutral) wire.

I'd agree with TZ - much simpler to just use the neutral wire (blue) on the later switch.