From a 1970's historical perspective, when comparing two similar models of this level, from the same manufacturer but different years, chrome fork ends and center-pull brakes typically pre-date painted forks and side pull brakes. Also, while it's not entirely clear via the pictures, neither the Professional 1 or 2 in the catalog appear to have eyelets on the dropouts. Again, elimination of eyelets was the typical evolutionary path. Hence, I believe the OP's bicycle to be older than 1978.