1985 Xj6 suspension

Hi, I am wanting to purchase new springs and shocks for both front and rear of our 1985 Xj6 Series 3 Sovereign ( Bessie) as we call her.

Bessie is in very good condition but even when we bought her in December 2005 the rear end was very harsh and thumped over bumps and this has only become worse over time.

I am wanting to replace the rear and front springs and shocks and would like the car to drive as it did when new hence I'm not wanting some sporty springs and shocks I see advertised all the time.

Surely someone somewhere knows what the original spring / shock specification / rating and can advise me as to which new springs / shocks are made to this original spec?

I have tried many places and they seem to want to sell sporty ones..

If anyone knows what the original spec was or who makes original spec springs and shocks I would really appreciate their input.

Cheers Paul David Cross, Victoria Australia.  I will try to have some photos of "Bessie" here for you to see.  Note the rear seems a bit low to me, I am hoping new springs / shocks will get her where she was when new without the current thumping from the back end.