Hi Keith,
Three options:
try
http://www.flatattackracing.com/
They are an Australian Company. In Victor Harbour (South Aus). You might need to email him.
Autopro are always pretty good with the small stuff. As long as you have teh Outside diameter you are halfway there (You can use the MAC's website for a reference size from their parts.....)
Otherwise an engine re-conditioner should have the size you require.
If you have no joy with any of the above, PM me & I will look into it after mid January when everyone recommences work.
Ian