I went through this on my '57 and ended up using aftermarket polyurethane. Only took a couple of years for them to thoroughly disintegrate so I recently had a fabrication shop make me some out of 7075 Aluminum round. The spring eye ID was 1.0625" and the OD 1.5". I found two 1' pieces of 1.07" and 1.57" round stock on eBay at a decent price, had the fab shop cut them to length (smaller diameter as the spring eye bushing, larger as washers to hold the bushing in as shackle spacers)and had 7/16" holes drilled in all. Cost was under $50. Not stock but painted black you can't tell the difference and it'll be a long time before I have to replace them, if ever. Bronze bushings used to be standard spring eye bushings on real old pieces.
