[MattW]

My car is currently in bits, so I can't check anything.

However, there are 2 simple things that you can do.
A) cut some from the lower shock mounting ball gripper - I'd suggest 1-2mm.
B) get some "lower" spring cups - as I said on the other thread, I'm 99% sure that AE B4 ones will do it.

Your suggestions on shock length will make no difference - either with spacers or shaft length will make no difference to ride height, only to droop. Rebound will make no difference either.