I am guessing either very late 1970s or, more likely, early 1980s. The single set of water bottle bosses is typical of that era -- by the mid 1980s, a second set, on the seat tube, had become almost universal. If it has a 6-speed freewheel, that would also befit that period. The under-the-bottom-bracket cable routing is also a 1980s thing.

Those who have seen pictures of Capo #1 know I love the red with the white head tube.