ok, so I know it's a long shot, but anyone got one spare?
Not too fussed about rings, and although 175 preferred anything 170 to 180 may be ok.
I had the IRD Vortex cranks (they were quite similar!),
sold them a while ago
This is what Joe B. had to say about it:
Both Vortex models were designed by me. I essentially sold the rights to make them to InterLoc.
The original Vortex cranks had a round, tapered cross-section and a machined spider. The later version had a cross-section that was more square and an investment-cast spider. Both are made of chrome-moly steel.
I still prefer steel!