Adapt VSS to early car mechanical speedometer?

My 1983 LT1 car has a turbo transmission installed that has the Porsche the speed sensor/sender, but the sensor is currently unused because - not needed for the early car with the original spindle and mechanical speedo cable.

However, about a year ago I had struts and spindles installed from a 1986 turbo so I could use the larger turbo brakes.  The 1986 spindle was drilled by my installer to accept the speedo cable threaded through it.

Reading on another forum, I've learned that drilling the spindle is a no-no from a safety point of view and could make the spindle prone to crack and break. Neither the installer (friend) or myself were aware at that time that this could be a safety concern (yes, I'm that stupid).  I want to replace the drilled spindle with an unmolested one.

I understand that a mechanical speedo can be driven by an electro to mechanical converter motor that takes a VSS signal and spins a motor and cable to drive the mechanical speedo.  

My question is whether the existing Porsche speed sensor already in the transmission can be used with one of these electro-mechanical units (such as the Dakota Digital ECD-200BT)?  Does it output a proper VSS signal ?

I don't want to use a GPS speedo because I live within 3 miles of three school zones with traffic cameras where they ticket you for literally any speed over the speed limit.

the sensor on the 85.5+ transaxle is just the top portion, inside the transaxle there is a gear drive that would normally drive a cable. take the sensor off the top and the transaxle is now capable of driving a speedometer cable.

you would need to find a shop that builds speedometer cables (something that was common years ago but is increasingly harder to track down) to build a cable. the other concern would be calibration, im not aware of different gear tooth counts for the speedometer drive gears in these transaxles.

Thanks for the tip. An extended speedo cable definitely sounds cheaper and potentially more reliable than an electro-mechanical conversion box. That said, calibration does sound like the issue

...anyone here know how to solve the calibration issue?