Brit pistons are fine, no problemo, its age and price thats the hitch. As long as I can find some in a wreckers.
I mentioned Japanese cars because New Zealand yards are full of 'em. Not much else here anymore.
Maybe Mini or Jag or Landrover pistons will fit......i'm all ears.

Thanks for the link, but money isn't burning these pockets sadly.

Cheers
Phil