I finally got around to doing something with some Wossner GTi6 K9182D050 pistons I picked up cheap. They're going into an XU10J4 block with an XU9J4 head, fitted with 36.5/30.0mm valves and some lairy cams. I had to take a bit off the dome, otherwise they would have been 14:1. The other issue is the radial clearance required for the larger valves. I had to go 0.5mm deeper as well, to get the lift @ TDC clearance correct. They really are cheap and nasty pistons. The deck isn't even parallel to the pin.