No, not at all!! That clamp requires a straight seatpost necked down on top to take the circular clamp. Just using the outer cups and bolt won't provide the inner rail clips. He can either find the missing pieces at a bike shop if he's lucky or buy a complete new Kalloy seatpost for not much money.

To the OP: The proper diameter for the replacement seatpost can be found by removing the current one and reading the diameter engraved at its lower end.