There are many ways to get your geom, this may be another way that would be easy to do also.
I have Boolean subtracted most of the solid away just for simplicity (not really necessary)
Create a surface (create its own layer) to rotate / rotate around X / X0 Y0 Z0 / rotate surface up in this example to where it captures the most ID of solid / Boolean subtract solid from surface / rotate surface back to X Y / Extract edges from solid (which in this case is the surface) / Blank surface / trim and join lines as needed.
Hope this maybe helps.
RAF.