The four blocks (two in photo) look original which makes them thirty four years old.
They look as if the should be used with the spinnaker.
Does anyone know why they have a foot line and metal clip attached?

They are snatch blocks, the line may attach to the life lines to hold them up when they are clipped to a toe rail or chain plate. They also stop you fumbling them over the side.
The four blocks (two in photo) look original which makes them thirty four years old.
They look as if the should be used with the spinnaker.
Does anyone know why they have a foot line and metal clip attached?

As Jolene said and they would be for spinnaker sheets.