There are quite a few commercial options available that come as a kit with wiring, connectors etc
For example, you can use the Acumen one I used with mounting details in this thread -
Procycle Digital Speedometer Retrofit
That was the drive for the Acumen Digital Gear indicator which is actually available separately. I actually used the single sender to drive both the gear indicator & the speedo together. Other options would be the Veypor drive kit (only comes with one magnet but easy enough to add more) or options from Dakota digital if you care to do a search on those.
It sounds like you should be safe enough in using one of these per the info from Stlakid and then just playing with the number of sensor magnets (either 2 or 4) to see what gives close to calibration. Then add one of these Yellow box calibration devices in-line to fine trim it for determoned accuracy.
YellowBox
[ This message was edited by: DEcosse on 2006-12-09 13:52 ]