Hi Andrew,
I have a set set aside for a 54 SS currently under build, so sorry, not available; they are hard to find.
I have attached pic of set on my 54 GF.
For my last couple of SR's, Ikon (Australia) built me set(s) of their current (4 way adjustable dampening) shocks, using the (classic) spring covers. These are fatter than the standard SA shocks, but smaller than the 54 shocks; in-between. Plus, they are are modern (good performing) and externallly adjustable and rebuildable shocks. I recall writing to Geoff; very helpful..
i would go the same way again. Approx $500 Aus / pair for the last set (6 years ago).
Richard