The ad says 1965 261,must be a misprint,last year for the 261 was 63 at the latest.The engine also appears to have the 1954 and earlier type water pump and the valve cover type is only found splash oil 216/235's and the 53 PG full oil pressure 235.Some people swap over an early valve cover on later engines to keep a vintage look, but this seems unlikely here.
best to check the block numbers first.