Hillclimber147, Could a 90mm piston ( CR) be special ordered with the piston pin hole machined in the KX location ? Or could you purcahse the unmachined piston forging and you machine the pin hole to KX diameter and location. That would allow your 90mm bore,rod would be unchanged and port timing would not be changed. Using a shorter rod increases the thrust angle and places more thrust on the cylinder wall, not good.. And moving the barrel upwards, increases the crankcase volume which is not good in theory. I see no gain in using the CR rod except that it would fit onto the CR piston.
Since we are only talking here, I thought that moving the pin hole was easier than changing the rod and fussing with barrel height. John