What is pin 46 of the ecu?
Do you have a electrical diagram showing the o2 sensors and pin out to the ecm to post?
I would maybe check continuity at the pin on the ecu that goes to the 02 sensor in question and to ground (Guessing without looking at the diagram). Do this with ignition off. Your looking to find out if you have a complete circuit.
If continuity is infinite, you have a break somewhere in the circuit. If you are seeing zero resistance, you have a short in that circuit somewhere.
Either do above, or check voltage at the wire right at the ecm (whatever pin number and wire colour that is) that goes to the o2 sensor while the vehicle is running. Any voltage there?
stock block 347 w Bullet Forged flat top pistons, TW170 p&p heads, comp 35-775-8 cam, approx 9.6:1 compression, 72mm rear mount turbo, injector clinic 650h injectors, CircleD 2800 stall converter, Lentech valve body.