A machinable epoxy is an interesting idea. I think I'd try one of the glues first, and building up a solder as a second try. One thing I would wonder about is weather the glue would be a persistent containment that would effect the solder adhesion. Other question I have is would the 3 heat cycles the 531 forks would go through to replace the cantilever mounts would be a concern.
Last edited by bark_eater; 05-21-20 at 08:52 AM.