Steve, thanks for the feedback.
Good to hear the welded pivot pins seems to hold up. I wasn't sure if it would be hard enough to deal with the load and wear. I forgot to mention it, but another idea I looked into was to completely replace the pin on the pedal arm. But it is not easily removed without causing other damage, and sourcing a suitable replacement piece may be difficult.
Regarding the lengths of the push rods/masters. Luckily I found them to be pretty much equal on both on these boxes. But I agree that rod should be adjustable. You can adjust the free play by moving the pedal stops further in, but that changes the pedal position. I can see how that could be really awkward if the two were very different. But even if they are not, the pedal position would ideally be a separate adjustment from the master free play. I think mine are close enough that I will not need to modify the push rods, but if I do then I'd opt to make them adjustable like most other vehicles have.
And you are correct, the line nut on the clutch has a 13mm head....I was erroneously saying 12mm which is the thread size. Thanks for the correction. By the way, that 12mm nut is much more difficult the source than the 10mm ones.
The large end piece on my clutch masters are steel. But the more I work on the hydraulic systems and think about things, I don't believe the type of metal (steel, aluminum, iron) really is the issue with fittings freezing. Although the anodized coating on the aluminum may help, I found many nuts in other metals that did not cause problems during removal. In my case the biggest factor seems to have been the type of wrench used. That one I mentioned with the pinch bolt to clamp the wrench jaw tightly on the nut has a 100% perfect record for the 10mm nuts. Not having that style of wrench for the 13mm nut (I have a standard flare nut wrench) lead to destruction of them.