Ok, so I took that g-code, removed the header that was in there, and cut and pasted one from a file made by Carbide Create. I did the same with the footer. I also processed it with regex in a text editor to clean out the comments on each line. It worked perfectly.
Did a test on a piece of Foamular I had lying around. Results are extremely promising.
I surfaced the foam on one side to get it to the correct thickness. Here's the inside of the joint it made, note that the foam here looks nice because this is the side I surfaced.
It's reasonably square, for a joint made of dinged up foam from my drawer:
Here's a couple outside shots, as you can see I did not surface this side, and it looks bad. But note that the fingers all align nicely, and it's a nice looking joint. It feels snug - well, as snug as foam can feel, anyway. In general a very successful test!