1996 Specialized Ground Control - spring problem

I took pity on a rather sad looking Specialized Ground Control A1 recently.

At some point in its life, the rear spring has been replaced with a non-original item, and I'm now looking for an original spring (RST developed with Specialized) or a suitable replacement.

As you can see, the current spring is far too short for the shock. The original spring would have been approx 100mm in length and has '250' printed on it (I'm guessing that's the poundage, or whatever it's called?).

Any ideas where I might find such a spring (original or not)? I've looked on ebay and can't see anything suitable. Also, I know Risse make aftermarket shocks but they won't fit this type of shock body (the lower section isn't bolted to the swingarm - it slides and clamps into it).

Your thoughts are appreciated.

Cane creek has some nice stuff, check it in pages like https://www.tftuned.com/rear-shock-spri ... prings/c77