Originally Posted by
repechage
I stated 60's due to the Sport derailleur spring hole in the drive side dropout.
The 151 mm BCD crank also points to the 60's.
It might have a top tube surprise, an abandoned rerouting of a possible internal brake cable routing to three brazed on guides
It does have something going on under the top tube at the front. Nice 60s look to the lugs and a nice detail at the fork crown.