Agree the fork is probably a replacement but not only the transition treatments (domed, flattened vs beveled) but also strong hints of a rifled steerer so most likely a Columbus fork and betting this Nervex-lugged frame is Reynolds 531. Also the long campy DOs don't have portacatena holes (2) but a single return spring hole for the Sport or Gran Sport RD, so it's not a late '70s/early '80s frame, except maybe the FORK is about that era.
If OP will measure the headbadge hole spacing there might be a clue in that, too.