I am posting a photo of my Bob Jackson. I don't want to corrupt your thread but there are so few of them shown here, I thought it to be at least tangentially relevant. If you'd like, I will remove it.

Mine is certainly from the same era as yours. I am the original owner and it's also now over 50 years old. My best guess is there are about 100k miles on this frame - riding, loaded touring, commuting,... you name it.

It no longer has its original paint and during that repaint a few braze-ons were added. All the mods were later added by Jackson added to his newer models.