Shouldn't you just be able to locate a diagram for your ecu pinout. Find the vss pin. Pin a wire into that location on your olug, it should be empty, and then just plug that wire into the back of your plug on your speedo that feeds the speed sensor? My 82 was labeled on the back, I don't have a 3rd Gen one here to check, but I bet they are also labeled.
For the stop switch, you should just be able to tap into the brake pedal switch, right? Someone correct me if I'm wrong.