I wouldn't bother. I'm doing 5000 miles a year in a LWB and the steering is not an issue. Perhaps people are soft now? I simply would not parallel park, the forces on the steering are high, the rear visilibity is terrible even though we have a reversing camera, I reverse slowly to be sure and that seems to encourage people to step into my blind spot.
A Series is a 60 year old design and it comes as a complete whole that by and large makes sense. If you try to modernise it where do you start and stop? The area that most deserves attention on a loaded LWB is the brakes, 99% of steering is done driving along and there is simply no need to have that power assisted. What you do not want is to be able to turn a 50 year old high narrow vehicle quickly, its not a good plan.
If you look at the power steering conversions they are primarily done for one of two reasons:
1 The owner is getting old and cannot put suffcient force on the sterring wheel
2 The owner wants their wife/girlfreind to drive it
"1" makes sense and its a sad fact we get old, but I serisously question that any wife or girlfreind who refuses to drive a series could be swayed by lighter steering. My own partner flatly refuses to get in our Series let alone drive it (a plus I hear some of you say...) and her list of reasons doens't even include steering. (For those who ask, smell is top, followed by door hight, gearlevers in the way, metal everywhere, noise, body roll, door handles....and so on.)
