speedo adjustment gearing

["Janssen, Lee K" <lee.k.janssen@lmco.com>]

Now that I'm running with the wrong wheels, tires, & transmission I need some 
sort of gearing in the speedo cable to get the speedo to read correctly. 
I'm sure those of you who do time / distance racing know exactly what I need 
and will be more than happy to help me spend $$$.
Unexpectedly I actually intend to use this gearing for the intended purpose.

Thanks in advance to all of those who respond, you guys are a great resource!

Lee