When I looked at the ports on the DR cylinder compared to the ports in the LML cases, I realized that there's more than a bit of a mismatch. The ports on the DR are MUCH smaller than the LML's.
Thus, I've decided to open up the two side ports on the DR.
While most of what I've found on the topic seems to be about expanding the porting in cases to match cylinders, I assume the opposite is true.
Thus, I'm thinking that my cuts will look more or less like:

or, from the other side:

(The cuts would not extend past the current lower edge of the cutout, I just extended the lines down there. Also, I now realize green was a really poor color choice for marking the pictures up.)
So I now have a number of questions:
1) Does my basic approach look correct of what I'm cutting?
2) How important is it that I round the corners of my cuts? Can they be pretty much square if I chamfer them?
3) What all should I polish through there?
4) What else should I consider cutting as long as I'm doing all this?
5) (extra credit) I also have to replace the crank. Would a cut crank make sense here?
Thanks, everyone!