Here we have the steel wheel braking surface with greek key pattern typical of 1970 -72 , but yet several features that appear quite a bit later than that
(the boots on the dynamo, the hex key fixing bolt kick stand )
see if :
- s/n also appears on White paper tags at the bottom bracket area ( look as though they were typed labels ) and scotch taped over ( or only as in the blue bottom bracket shown in this pic below ) will look pics of a the later style tag s i have somewhere
-the dynamo wiring routing has braze tabs on the underside of the down tube / versus internal routing?
Internal routing would indicate later than 70.s , as do white paper s/n tags as well.
Those puegoet fendersets and lighting arrangements went on into the late 80's at least , and are most often seen with a smaller integrated fender mounted headlight.
( the corporate gifted Bianchi bike I owned also has the dutch style ladies step thru frame, full chain case, drop stand, intergrated caliper lock and the bell was inscribed this was a 1988 and given as year end holiday gift by / among very senior management / board of director level . Came to me via a senior ex pat Diplomat serving here in the Swamp. point being nature of the work done wasn't along the lines of manual or even skilled labor .... certainly a very white collar and pressed )