So I had a few days to try to sort something out at the front. I had been cautious about using randomly repaired service units, and uncertain about how much damping would be right. So I had previously tracked down Peter Caldwell at World Wide Auto Parts in Wisconsin (!) to talk about his adjustable recreations. Peter uses an externally plumbed needle valve to emulate the old adjustable Armstrong 22 - which suffers from a high unobtanium content.
But they fix a problem - the front left shocker provided no resistance over half its sweep. And they will allow me to calibrate better the front damping after I have some kind of setup.
However, I recognise that something else will be required in time.
While I was in there, fitting them, I also sliced a few mm off the droop bumpstop (a Midget item I believe) in search of a little more travel.