Electric Tach conversion?

[Sprinklerhead]

Has anyone ever done one?  I'm converting my front end over to a GSXR-750 and I'm trying to use the stock GSXR gauges.  The speedo will work without a problem since it's hub driven, but I'd really like to use the GSXR tach instead of the ugly GS500 mechanical tach.  Looking at the wiring diagrams for both bikes, I'm guessing I can hook the tach up to the wires coming from the signal generator.

Any help is appreciated.

[hammu]

spark plug wire

[dgyver]

There are 3 wires on the tachs:
red = positive
black = negative
orange = signal, orange/white from ignition box

[Sprinklerhead]

There are 3 wires on the tachs:
red = positive
black = negative
orange = signal, orange/white from ignition box

Thank you.  Saves me the trouble of testing each wire.