Guys, many thanks for all your comments and time taken to pass on your knowledge. Much appreciated as always. And I hope you like the picture-book blow-by blow account I'm posting here as I work through my to-do list (and uncover more problems as I go!).
@ALB and @Gordon Nichols - point taken on the steering box. I'll strip it down, get new seals and fill with oil not grease. I thought I was doing the wrong thing using grease but I couldn't find the relevant post on here. Just shows - a little more patience using this site saves me untold pain in the garage!
And yes, Gordon, I am havin' fun, despite making a few rookie mistakes. :-)
As for the oil cooler, it absolutely makes sense to move it back into the rear wheel arch and lose 16 feet of hose. Gordon, you mention wall friction - I knew there was a reason for not having the cooler up front and you nailed it. More commonly known as pipe friction, there is a known formula for calculating the loss of pressure along a given length and ID of pipe by a fluid of known viscosity. I know of this phenomenon more because I follow pro cycling/Tour de France etc - in a sprint finish the riders always ride by the barriers because there's less headwind than in the middle of the road. But for hoses, "short is sexy" works for me.
I'll go out and have a look in the garage later (once I've finished some 'real' work for the day to help pay for all this!). I can feel the huge Sidewinder-style exhaust will cramp the ability to locate everything without it getting too hot or close to the wheel. And tryng to bend steel-braided oil hoses in any kind of tight radius is near impossible, as no doubt all of you know.