Post-ironic,
The original Bilsteins, P30-0061 (front) and P30-0062 (rear) is the route I went down. I managed to source a used pair of both (my friend source a NOS pair). I was lucky to have them re-valved in the US, where I got them with the help of a friendly Hybridz member. I can't remember which way, but one pair was re-valved, while the other set was too far gone. they could be re-built at a un-economical cost, but they found another shock that would fit and close valving. And it wasn't the VW ones. I will have to dig them out for what they are. The good thing is the Bilsteins can be re-built.
I had them re-valved by giving them the spring rate I am using, and the car weight. The key to good suspension is getting these to work in unison. Most just throw some springs/shocks expecting brilliance.
It wasn't a cheap route, but for me, better than the cutting shock towers and adding some modern stuff in. Keep it looking original.
FYI, The old Bilsteins are clour coded for front (green) and rear (yellow- I can't quite recall, or the other way round) , but I this doesn't always be true, as I have a set with the colour on the "wrong" shock. The stamped numbers are the key.
The "wrong" coloured shock could be for sale....but would need re-valved/serviced.