1986 ELCAMINO. HOW MANY OXYGEN SENSORS??

I wonder this because I have inherited an 1985 Conquista El Camino. If the car has been altered and now has dual exhaust front to back with no catalytic converters - It will not pass inspection - so If I choose to not go back to stock exhaust , do I need tow catalytic converters and if so ( I assume I will) do I put two O2 sensors or just the one on the drivers side before the converter? Today i failed the Idaho emissions, the last time it was inspected was 2016 Texas - I don't have a clue how it passed though, My Dad must have been a big tipper or something. It has a o2 sensor in it but I doubt it works.
It has regular stock manifolds, someone took them off and when they put them back on they smashed the dip stick ( drivers side) so I can't even check the oil. I am going to get headers for it if I can get these bolts out. I wonder this because I have inherited an 1985 Conquista El Camino. If the car has been altered and now has dual exhaust front to back with no catalytic converters - It will not pass inspection - so If I choose to not go back to stock exhaust , do I need tow catalytic converters and if so ( I assume I will) do I put two O2 sensors or just the one on the drivers side before the converter? Today i failed the Idaho emissions, the last time it was inspected was 2016 Texas - I don't have a clue how it passed though, My Dad must have been a big tipper or something. It has a o2 sensor in it but I doubt it works. It has regular stock manifolds, someone took them off and when they put them back on they smashed the dip stick ( drivers side) so I can't even check the oil. I am going to get headers for it if I can get these bolts out.