Thank you Steve for the suggestion, I'll try that if the webbing doesn't work out.
I also finally got around to implementing Steve's other suggestion of an anti-rollbar! I got the parts from Alun a year ago from one of his Dolomite Sprint projects, but only just got around to cleaning them up and painting them. I struggled to fit the anti-rollbar and
consulted this forum for advice, the method that worked for me was:
a) Lower the car onto its wheels so the suspension is at normal ride height
b) Install the drag strut mount onto one end and install into one of the drag struts. Loosely install the washer and nut so it can't pop out.
c) Install the other drag strut mount onto the other end and fiddle and swear a lot until the hole lines up so that you can install it into the other drag strut. Loosely install the washer and nut.
d) Fit the subframe bushes and subframe mounts. Cable tie the top hole of the subframe mounts together so that they can't pop apart
e) Push the anti roll bar up the subframe until the holes on the subframe mounts are aligned with the holes in the subframe
f) Spend an enormous amount of time and swear a lot more trying to get all of the holes aligned and bolts in - the top hole is cable tied, but get a bolt through the lower hole and stick a nut on it so it can't pop out. Then you can cut the cable tie and work on the top hole.
Over a 30 mile test drive of country roads and motorway it seems to have made it feel a lot less wallowy and overall much nicer to drive, not a bad thing in a slightly underpowered car in modern traffic. Although I have tried to keep this car as original as possible, I would consider this a safety improvement and therefore worthwhile.
I also installed the later drag struts from the Sprint, as my early car had the early drag struts and recall kit
fitted as part of the 1973 front suspension recall and this would have interfered with the ARB.