Yep, you can even see the outline of the starter mounting face on the midplate. I would (and plan on with mine) just bolts up the starter to the plate with bolts and nuts, and trace around the mounting flange. Bingo - there's your cut line.
On the spacer, with your 1/4" plate, I'd probably choose to run an actual flexplate spacer on the crank than use 1/4" washers between the flexplate and converter, but that might be just me. I've seen some thick midplates come with those spacers.