Miata Turbo Forum - Boost cars, acquire cats.

G'day anyone,

I've lately been looking at my wobbling speedometer and wondering if it's possible to swap an NB gauge cluster into an NA. I know I'll need to swap over the oil pressure gauge, but that'll be something for another thread.
I mainly want to get rid of the speedometer cable, because it is old and pretty suboptimal. Since the NB uses a digital speedometer, I've been wondering what would be needed to have the VSS Signal pass through to my v1.5 DIYPNP. Although this wouldn't be neccessary to get the cluster working, it would be a nice addition.
As far as I understood up until now, is that I would need to make a "frequency to voltage" circuit in order to make MS understand what is happening with the VSS, then feed it into a spare ADC port.

Would something like the attached image work on the DIYPNP? Where would I have to connect the ends of the circuit, and what would the resistance need to be for the 2.5V at half the top speed? What capacitor would I need for the NB sensor? (How many pulses does it generate per wheel rotation?)
I can read diagrams and solder electronics together, but designing circuits from scratch isn't really what I'm good at.

http://msextra.com/doc/ms1extra/pix/VSS.JPG

Before anyone is commenting "Just buy an MS3X", I don't really have those amounts of money leftover at the moment, so just please spoonfeed me a bit.
If it'll work I'd be willing to make a guide on how to do it, to prevent any future people from asking the same stupid question.

Why do I want to do it? I want to be able to display vehicle speed, gears, fuel economy, power and torque in TS/MLV. And I might want to make a digital gauge cluster at some point.

Thanks in advance,
Jay