The bearings in my dog bones are pretty crusty. I've scored a pair of Crono dog bones off yahoo auctions in Japan to replace them, but that 's not really going to address the maintenance problem - it's a king sized pain to get them out to re-grease them.
I was planning to get a pair made up with grease zerks and use
bearings with 10x20x0.5 shim rings ... but how important really is it to use needle roller bearings? Would it be ok to make up replacements just using spherical rod ends?
Rod end could be used, all race cars use them, but for a road bike it would be a good idea to fit rubber boot over the spherical to keep the crud out, many bikes use greased bronze bushes so that could be another option, both rod ends and bushes would need more regular greasing than needle bearings.