if you still need a mk1 spring, maybe I can help you. I have one spring, rusty, but seems to work well. Length is about 266 mm, wide end is 42mm, small end about 36mm. As fare as I know, all springs in Douglas MK postware cycles are the same. I would sale it for 30 Euro. But the postage, even economically, from Switzerland to Australia is rather expensive, about 35 Euro I think. Economical delivery will take about two weeks. For payment I suggest paypal. Send me a pn with your address, if you are still interested.
Happy Christmas and a happy new year!