If you want to swap bits from your cluster, with a caprice cluster, then you are going to be out of luck...
(Been there, done that, and spent bucket loads of $$$$ trying to get a E3 Grange cluster to physically fit my Calais)...
Actually, none of the cluster parts are interchangeable (The cluster board, needles, face, screen and chassis are all different as the Statesman / Caprice cluster has its temp and fuel gauge elevated above the speedo / tacho. (They are also positioned further outward than the SWB clusters).
If you want to fit the cluster, you will need the Statesman / Caprice crash pad, passenger airbag trim, silver trim spears, lower radio surround, and radio.....
It would only be worth while if you had access to a statesman / caprice wreck, and the amount of trim bits you would need to source would cost a lot of $$$$ of buying from Holden.
Radio and Cluster would also need programming, but in terms of wiring, everything should be there.
(If your SS is a series I, with a non LCD screen, you will also need to modify your HVAC HCE to fool the headunit in to thinking you have Dual Zone Climate Control)
I hope this helps.
(P.S. I have a brand spanking new E3 Grange cluster if you still wanted to go ahead Lol !)