hi folks ,
Have this rather scruffy Bertin frame which I intend to give a makeover . Trying to nail down the date . Hopefully you knowledgeable folks can help ?

specs as follows

120mm OLN
26.4 seat post diam
milremo dropouts
three top tube cable guides
dynamo ? tag on rear stay
no lever brazeons ( came with clamp on suntour)
english threaded bottom bracket and head set
numbers stamped on left rear dropout 56 (size?) , 8* (cant read second digit) and 8688 (serial no ? )
Any other info needed ?