Just some quick photos of the combustion chamber shape, nothing precise, for discussion. I guess this is nominally a wedge shape, but it's a very deep chamber in the head with a large double-hump on the piston. It seems designed to push maximum heat into the head! Lots of surface area.

Here's a piston in it's hole. Note the big hump; the second photo shows the height of the hump (the screwdriver as a depth guage) down to the flat land that is level with the low flat on the piston.

These photos show the approximate (very!) depth of the combustion chamber, with my finger as a depth guage. It's not really visible, but in the last photo you can barely see the shallow shelf, about 1/8"? below head flush.