I've been following this thread and have bought a pair of rear shocks supposedly from a VL Commy. However, when I got them, they measure 650mm fully extended, compared to the 500mm or so from the factory zook ones...
I've put them in as a trial, to see what they'd do, and they provide a ridiculous amount of downward travel (as expected) and of course the factory springs are far too short.
Here's some pics of it with about an inch to still go.



I'm tracking down some C33 Laurel/A31 Cefiro rear springs at the mo, but pretty sure they'll still be too short to be retained between the stops. What I'm wondering, is whether it'd be any good to weld a small length of pipe to the bottom spring locator to guide the spring back to it's seat, and stop it falling out on the ground? Longer springs to suit the shock length would be an obvious solution, but it'd likely lose upward compression, and end up being higher in the back than the front could practically be lifted to match.
Any thoughts/ suggestions?