So - I don't want to go over my whole project. It's here if your interested/bored:
I'm LHD now. Installing the P38 steering box because of my build. It creates an issue for the panhard mounting because this box hangs down so far (and is therefore stronger at the output bearing. anyway...). A friend suggested I could swap just the panhard mounting back to the RHD side. I have the RHD upper bracket (I'd reinforce this as it used the steering box as a partial brace). Axles are all built with both handed mounts.
Only issue I could see is bump steer: as the front suspension compresses, the arc/left hand motion of the axle would create a right hand steering input. In bad design cases, this can create a real drivablility issue and oscillations. Anyone heard of, seen, driven a vehicle set up this way? The defenders are pretty spongy and have a fair amount of bump steer as is....