'95 S-10 PCM question

[Jmf5678 at aol.com]

I have a 1995 Chevy S-10/Sonoma with the VIN-W Vortec 4.3L CPI V6 and 4L-60E 
auto. trans.  It has the flash memory PCM, and as many of you may know, this 
computer is very hard to work on.  It has the OBD-II diagnostic port under 
the dash but the computer is only OBD-I compliant.  To my knowledge, there is 
no way to bypass the truck's electronic speed limiter and recalibrate the 
speedometer.  I changed my axle ratio from a 3.08 to a 3.73 and added low 
profile tires, so my speedo. has been off by about 15% or more.  So if any of 
you guru's know how to perform these mods, please let me know.  Thanks