Heres one for ya - need help with car speedometer

Hi guys, this ones not computer related, but this is the best place i get elecrical advice.

I'm upgrading the engine and trans in my car. The problem i have now is that the new transmission has an electronic speed sensor, and my speedo is the mechanical cable type. Now the first reaction is to just replace the speedo, and this is definatly an option. But i want to keep the stock look of the car, so i was thinking of creating a device that will convert the PWM signal from the VSS (speed sensor) to a mechanical output.

First up, would this be possible? I have basic electronics down, but i don't know what would be involved here. I can solder and all that so i could build it but i need help with the design and components.

The VSS is a Nissan one, which from what i can find, is a PWM that puts out 2 pulses per revolution (or 2000 per mile). I have yet to confirm this however. I don't yet have the ratio required for the speedo input (how many turns per kilometer an hour). I was going to get a brushless motor for a remote control car or similar for the output. Something capable of high rpm, and a brushless (probably an out runner) because they can operate at very slow speeds. Input to the device would be 12v, and it needs to be adjustable so that it can be calabrated properly. The speedo is in KPH.

Any help would be great! Also I am aware of a device called Cable-X which performs this funciton. I don't think it will work on a Peugeot though...

I suggest you buy an entry level book on the PIC microcontroller, then find out how many RPMs you'll need to turn the speedo input, then select an appropriate motor to turn it. if it's not too fast you might be able to use a stepper motor, that way you'll have pretty accurate control of the position / speed. not sure what kind of drive is necessary for the motors you're talking about, but if it's like the RC motor i have seen used for a mini-mill spindle, it has a dedicated 3phase driver for it. but that one was many K rpm, dont think that will be necessary for a speedo input, i recall playing with one as a kid while my dad was workin on a car, I could get it to go up a decent ways from just spinning the input with my fingers.

but in the PIC you should be able to read the PWM without too much work, then convert it to a speed that you can scale by some numericcal value, then send that value to the motor's output to set the speed of the motor. hope this made some sense.