I have managed to get a batch of Kingpin 175/80/14 remoulds with the "correct" pattern (which seems to have a different name depending on who you talk to). If anybody wants some please contact me or Dave Haizelden or leave a note here and I'll get in touch.
They are £27.50 each or £25 for 4 or more. We can either bring them to the start of a trial or if needed I can courier them out for £7.50 a pair.
I hope this will be of help to some people as it seems a lot of the possible sources of these tyres have dried up!