Lambda Probe on pre cat e34

Any of you techies know if my pre cat ('89) e34 would have wiring and support for a lambda probe? I'm going to fit one as part of an lpg conversion, but if if  the ecu stuff is in place, I might as well use it for petrol too, prob improve mileage. The book says that the ecu runs open loop if it doesn't detect a signal after a preset period from starting (as a fault recovery) on cat vehicles, so I wonder if, where no cat/probe is fitted, that's all that happens. Incidentally, the veh spec sheet from bmw says it has 'cat preparation' fitted from the factory, presumably anticipating possible need for retrofitting of cats. Surely if that was anticipated, it shouldn't need the whole injection system replacing to the later cat version.