Here's my 1977 Centurion Pro Tour (American Market) now enjoying the sights, sounds and smells of Sweden's summer. Lundagård, Lund, Sverige.
The changes she's experienced since new are a Sanyo dynamo hub in front, Shimano 135 mm hub (120 -> 135 mm for the rear triangle!) with an 8 speed mountain cassette, and now a modern, cheap Shimano Acera RD to replace the "finally gave up the ghost" original 1st generation Suntour Cyclone GT. That one busted on my first ride here in Sweden. It had been giving me trouble before the trip from California to Europe, and I think the fact that it shipped lying on its side wasn't any help...
Some of these changes were done before I ever knew anything about Sweden (the Brooks B17 and dynamo hub lighting setup), others after I realized I was going to be living here (single-wall 27" rear wheel to double-wall 700c with cassette hub) and hoping it would haul my behind favorably all over Scandinavia and Europe now that I have more vacation than I know how to handle.