Mark, I think you know we need more precision in these measurements. A 0.5 mm ring gap is 0.020", which is not very flash at all for new rings in a good bore. I put new rings in a well-worn (0.007" bore wear, compared with a service limit of 0.010") GXV120 a couple of months ago and the gap in a new top ring was 0.015". So, it sounds as if your bore may be fairly close to the service limit for wear.
Measuring the crankpin at "37 mm" does not get us anywhere: you need micrometer measurements, or Plastigage. Remember, we need to measure the maximum clearance, and that will be with the crank 20 degrees past TDC, and with the Plastigage across the bearing in line with the centerline of the rod.
