I recently built a 700r4 with a pro built s/s kit. The trans came out of a 93 chevy pickup. I was not aware that my speedometer buffer would not be compatible with the 40 pulse per revolution signal that the trans. was sending. I called a place named SPECMO and had the program a module for a truck with 3.73 gears and 25.7 inch tall tires. They only charged $75 shipped and they provided the module. I then compared the schematic from the camaro to the schematic from the truck and wired it accordingly, The speedo works perfectly. I wrote this because I searched it for 3 days and all posts say it cannot be done and the output shaft must be changed to the camaro style.
Hope this helps.