SHA Tin's stables complex is poised for a multi-million dollar redevelopment scheme it was revealed yesterday by the Royal Hong Kong Jockey Club, who also announced the successor to clerk of the course John Jeffs. He is Australian John Ridley who is currently racecourse and projects manager at Auckland Racing Club in New Zealand. Ridley, 40, is responsible for Ellerslie racecourse as well as the Club's training complex outside Auckland. He takes over from Jeffs at the end of July and will immediately become immersed in the redevelopment of Happy Valley racecourse where the track is to be completely torn up. But his appointment must also be seen in the context of an on-going feasibility study into the redevelopment of Sha Tin's 800-odd stables that were built some 20 years ago. Major General Guy Watkins, the Jockey Club's chief executive, said last night: ''It is something we very much hope to be able to achieve.'' The scheme will take a staggering three to three-and-a-half years to complete. The current stables are perceived as not up to the needs of modern racing which features a marked increase in the quality of thoroughbred stock racing here. The Club are particularly concerned about the general ambience for the horses which are confined to their stables for the vast majority of the day. ''Understandably, the stables are not as good in the 1990s as they were in the 1970s,'' added General Watkins. ''The horses do not have a variety of tracks to run or work on and they are in training for much longer than horses in other parts of the world.'' Any building project could only advance on a piecemeal basis with new stables being erected before old ones were pulled down.