[Shiraz (Ray)]

good going Jorge - the primary mountings on these need mods anyway and you appear to have come up with a usable system that also includes moving the mirror forward.
As a possible alternative, did you consider using blocks between the back ring and the mirror ring? if you glued some blocks on the back ring you could run the screws through them to give some lateral support to the screws - while using short springs. Might make collimation easier and if you glue them they could probably be removed if you want to return the scope to original condition. And it might be possible to do without those dreadful locking screws and all the complications that come with them.
anyway, thanks for an interesting post. regards ray