So the block is now ready to go on - it's time to gap the rings and fit them to the pistons.
I bought my rings from FW Thornton after asking both them and JP in Australia to quote. I had asked Drags as well, but the GPM rings they supply require the ring grooves to be machined to depth - and wisdom from the AOMCC forum suggests this is not easy.
So, having a modicum of engineering knowledge and some measuring tools, I read up on rings & piston design courtesy of Mr. P Irving's writings and set about sourcing the rings from basic dimensions. Duncan Rowley (who is a very helpful chap) at Thornton's came up with this set of rings from my dimensions:
We have our rectangular top rings:
And our Napier pattern second rings (this one is upside down):
And the oil control rings:
Speaking of which, don't forget to clean out these holes:
These are there to clear the oil which the oil control rings scrape off and return it to the sump.