The Elite springs are softer. The shocks are the same as Non Plod/non LSC.
There were a few later retail Omegas in Police use as they missed the cut off for the final production run so we're forced to buy retail cars from dealer stock. TVP and Scotland got pretty much the entire final production run of RHD Plod spec cars.
Can't help on the colours, my plod still had it's original springs at 265k miles, I put Irmscher springs and shocks on my 3.2 Elite estate because the originals were done at 150k. My 2.2 GLS estate got Sachs shocks and Kilen HD springs because the originals were done at 125k. My 2.2 Sport had it's original LSC suspension on it because it had only done 28k.
The other 10 or 12 cars I did suspension work on either reused the springs on the car as they were or fitted Kilen/Eibach as required by the respective owners and if the springs were reused then they went back in their original position ie left or right.
There are, AIUI, the following variations:
1. Engine type: 4 pot petrol; V6/2.2 dti; 2.5 Dti.
2. Trim: GLS/CD/CDX; Elite; LSC (Sport/MV6); Plod etc.
3. Steering wheel side: LHD made allowance for driver and battery on left side.
4. Body type, although this only affects the rear as the options become saloon/estate; self levelling/non levelling/LSC/plod
Within the above matrix there may be some crossover regarding spring lengths and weights. The end goal was consistent ride height across the board (673mm rings a bell) or LSC (15/20mm lower) regardless of axle weight ÷ 2.
Aftermarket only allows for engine; standard, lowered or HD without the nuances of trim.
Irmscher allowed only for engine and body as their springs were identified by axle weight... An Irmscher catalogue of the time would give you an idea of the spring weights.
Standard springs will firm up an Elite slightly, and should be fitted if the self levelling is deleted, and Plod springs are a sensible option on cars used for load lugging or towing.