I bought a second hand rolling chassis and changed the spax bushes to poly bushes. I had to use the spax metal inner insert though as the poly one was too long for the lower wishbone gap. It was a doddle. If you were stuck you could easily file or grind the poly supplied insert a little.
Ward sell them as a kit, can't see how anything else could be much stiffer for a light car and you'll have to take yours apart to add the washers anyway.
Perhaps yours were never sitting right and forced themselves out? My original ones were one piece so can't see how they could go out of shape without being duf.
Sorry but dont understand the problem very well and am beginning to whitter
