Tanknj,
sorry that isn't working out. In the U.S. here are some other suppliers I would ask:
www.countrysidecycle.comwww.classicycleworks.com (where my engine is right now)
www.britcycle.comwww.britishonly.com (I hope they are still in business. This evening, their web site was dead.)
www.wesscottcycles.com (built my wheels, quite nicely, thank you)
www.motopartsinc.com (they're listing your part with a price, while they show no prices for parts they apparently don't have)
In the UK:
www.srm-engineering.com (almost a certainty, but around $40)
www.leighclassics.com (stop in there when next in southeast England; friendly, helpful and a great supply of parts on the store shelves)
Among these, I am 99 and 44/100% certain you can find your part.
Richard