Hi I think probably most people on this site would point you toward "dogsboss" for the shackles as he has an ebay shop if I recall (please correct me if I'm mistaken, anyone else reading this). As for the snorkel, UK was a bit disappointing in terms of buying off the shelf, however I made contact with a chap via ebay called shrekster no.1 & he explained to me how he made his with a peugot 205 exhaust & some pipe & stuff in true Blue Peter fashion. I'm sure there are more than a few folks on here who can advise.
Regards MJ