I had a little time to play some more, so here is the latest and more definitive piston, with oil control ring seep holes, cross drillings, and wire clip fitting details added. Piston skirt and crown thickness is still quite thick in places, but could be pulled down some more I think.

CAD model has been totally redrawn and updated from yesterday’s attempt, and this is now a very close approximation of the direction I will be taking, with a calculated bare weight of 520 Gr. This is a reduction of 60 grams on the first CAD version, and well within target to beat the all up weight of the original 85mm Panhard piston, which was 636 Gr in standard trim (Tigre engines sometimes had lighter pistons).