I have no problem mixing components' years or brands if the goal is to build a great functional bike. Chronologically or culturally correct components are nice for aesthetics, but for many bikes that's not the goal, not a high priority. My UO-8, like JE's and so many others here, has a mixture of functional components, mostly Japanese.

I do see something seriously wrong with that bike though. You really need to add a brace of links to the chain. If you don't then one day you will unintentionally shift to the big-big combination and then the rear wheel or the DO or you could take serious hurt.