Hi Rom
I obtained an allot piston from Dev Engineering that was machined in the way you describe.
As I had a second new set of Listeroid rings I used two scraper rings
After about a dozen short runs - before I got the cooling system sorted - i was turning the engine over by hand and there was a dull clunk, I rotated it gently in both directions and there was no further resistance so I put it down to 'one of those things' and ignored it.
I did a couple of short runs then a decent hour or so, loaded and unloaded, and then popped the big end to check the wear on the new shells, no problem there but there was bits of rings in the sump.
after pulling the piston I found the bottom ring had shattered, it looked like the piston had descended too far, the ring had 'popped' out and guillotined it's self on the return stroke.
There was some minor scoring in the bore, from the bits of ring that were still in the groove but nothing too serious, so I reassembled without the bottom ring. I couldn't see how the event had occurred, you can't see the groove with the piston at BDC and the original Lister cylinder is parallel all the way down, still with the Listard chrome and signs of the original honing.
Anyway it runs quite happily without the bottom ring, there's around another 5 hours on it now.
I'm wondering if it's worth getting the local machine shop to put in another groove, for a compression ring, between the gudgeon / wrist pin and the lower oil ring groove.
Weird, any light on the subject welcome!
Cheers
Stef