Could you make a mould out of MDF or similar for the bushes, maybe by drilling the right size holes in 2 or 3 sheets the right thickness of each step and bolting them together? If so, this would work :
http://www.mbfg.co.uk/polyurethane-rubbers/pt-flex-70-rubber.htmlThat's the "middle of the road" stiffness/hardness at 70 on the Angstrom hardness scale, roughly the same as the average car tyre for hardness. They also do a 20, 50 and 60 and an 85 which is about the same as POlybush/Powerflex/Superflex polyurethane bushes.
I know it is used in the USA by people with modified Golfs, Civics etc that can't get stiffened bushes for various suspension/engine/gearbox mounts and linkages and the drill out most of the original rubber and "back-fill" with this giving them a new, much stiffer bush. I still haven't got round to using it for what i bought mine for which is replacement suspension and ARB bushes on my Rovers that are now unobtainable. Must pull my finger out on that one in fact!
For £20 for the 1kg kit it could well be worth a try, better than having those spring hangers floating around! I think i would make a jig to make them holes line up, bolt it all together after cleaning all the original rubber from the metal parts and then pour in the mix and leave it a few days to cure properly. Apparently candle wax is a good release agent for the mould, i was going to rub it on the mould surfaces and then if it was reluctant to shift, shove it in a warm (70-80C) oven to melt the wax and then pull the bushes out.
Don't know if that's a helpful idea, hope so!!