I tried amayama and they confirmed that the heater hoses are no longer available.  No response from Road and Track but I would expect the same reply.  Repco don't have anything and could only suggest pulling all the hoses out and trying to match them up in the shop.  The other alternative is Gates publish a list of theri parts which can be used to replace the hoses so I might try that next.
 
Ah the joys of old cars!