I'm a little confused what you mean by "I opened the post processor to do a little editing, changing mm to inches". If you just set the units on your model and on your CAM workspace, the post processor should take care of generating the correct gcode for you. Looking at the tormach post, the only millimeter values I see are for the minimumChordLength, CircularRadius, etc...
Just to be sure, you are pressing the "Post" button when you're trying to create the gcode, not the "Open Config" button that would bring up the tormach.cps file in the editor.

Also, just wanted to mention that you won't be able to just reuse a post from another CAM program in Fusion. But if you've got a Tormach (I have a Series I PCN1100 in my basement) there shouldn't be too much you'll need to change that isn't in the Tormach post.
There's a ton of helpful people here on the forum. I'm sure once we're able to see your attachments we'll be able to get things straightened out for you!
Dave