magneto chain

hi all, I am doing up a1923 kelvin pet par 3hp single but the mag chain I have is to big I think it was of a motor bike, it don't fit the sprockets properly and jumps when its turning, would any kind body out there know where I can buy mag chain,,,,1/2in. between the pins by 3/8 wide I think it is the same as my Lister A. but I need 30 links,,If I could get the right size of chain I could make it up to length with connecting links, I tried all kinds of chain from bicycles to cement mixers, but I am kind of limited on the island so hopefully somebody will come back to me with  addresses, wishing all the best to you all,,cheers,,kenny