Hi soonerbills -
Looks like a 71-72 to me. I beleive the Shimano DRs/Suntour changers, saddle and foam padded bar tape later additions.
The rims, crank, GB stem and brakes are original, with the possible exception of the hoods.
I think you are right on the year. i remember reading or hearing here on the forum that the last two digits are the year but can't remember for sure.
I think the sticker was a "531" but is pretty well gone. Is there anything special about the lugs?
soonerbills, no, the bikes came with all European components in those days, so the derailleurs and shifters are replacements. The European parts didn't last long, which is why you see them replaced so often.
Tom, The derails are Shimano Crane. Are these desirable as a vintage pieces? I read they were the early Dura Ace models. The freewheel has a massive "granny" gear and the big chain is "big". Was this the norm for extra large frames or is this just a unique feature for this particular bike maybe a customer preference?