Thanks everyone! I appreciate you all taking the time to comment.

3larmer pointing out that postage would suck up any saving on the kit if I sent the crank to the US coincided with me discovering that you could buy the taps and inserts separately, so I've ordered a left-hand tap and 3 inserts. I have another crank with the hole not quite square to the crank face that I'm hoping to 'repair' with an insert, and a friend who wants a l-h insert (and now to borrow the tap).

Also coincidentally, the place I found that sold the parts individually was Niagara Cycle Works, the same outfit 3alarmer linked.

Thanks again!