I would roughly date it '74.
Since the fork has been replaced, I would check the front of the frame for ripples and/or cracks (if you have not already).
It's easy to tell it's not a '74. The Reynolds decal was moved to the down tube beginning that year.
Brifters would be as out of place as that saddle with its backwards clamp and that hideous fork
I wouldn't trust those plastic brake levers with my liife.