A 518/46RH trans only has a two wire plug for the OD. Power to one wire and ground the other. Its just a controll solenoid. It doesn't care which wire is hot or ground.
If your not using the PCM on your swap the TPS is not needed. That sensor feeds a signal to the PCM. The trans itself has no use for that signal.
To control OD just pickup a Hobbs adjustable pressure switch. Plumb it into the test port for the governer on the trans. Then adjust it to the MPH you want OD to come in at. The down side to this way of hooking it up is it will only go into OD at the set MPH. There will be no part throttle upshift. It will work if the main thing. Any time you would drop below the set point it would down shift to 3rd.
2014/93 W350 DRW, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, G56 SBC Con-OFE, 3:07's axles, 2" skyjacker lift, B&W flatbed