Okay. I wanted to run the top window port as wide as the widest part of the rear boost port.
mocked it up in my Half jug.
and. when the transfers JUST open. the top of that port will already be roughly halfway down the wide portion of the rear boost port.
sooooo.
I can either cut it as a upside down trapezoid, or make it square and the same width as the narrow portion of the rear boost port (same width as the previous "S" pistons)...
The pointed (stainless dental tool) marks where the top of the window port would be, when the ports open.
here is the top of the boost port (dental tool)
which is
roughly here... special note (making my calculations based on WOSSENER piston machining, as there is a big step cut there in the crown... )