Not exactly answering your question but years ago when I fitted a larger [Kmac] front sway bar to my P510, the stock sway bar saddles had no hope of fitting over the supplied bushes.
I ended up making some custom clamps from 40x2mm strap.
The bends had to be real tight so I could still use the original threaded holes in the front cross member.
Even then I had to use socket head bolts, a hex head was out of the question.
Also the original clamps had a pressing in them to grip the OEM rubber bushes and this of course was not part of the design of poly bushes.
If you know the bar OD you should be able to get some generic bushes from Pedders and such.
But from experience I doubt that you'll be able to re-use the stock clamps