Howdy,
I don't know if you will find exactly what you want as to import geometry and then plot code introduces so many variables when you want to compare existing code.
But a simple, (or maybe not so simple) depends on how you use it and set it up, Baclplot Program is a program called inplot. Go to
i-Logic Software and grab yourself a Free 30 day Full Version to use.
I bought this years ago when it cost me around 1k, now I see it's only $150. for one seat.
As a CNC Editor I have found none with the power and versatility to match this one. I use it for both Lathes and Mills.
Just to view the code is now a pleasure as I can configure it multiple ways. I can assign colors to each code word so G and M Codes jump out at me and Speed & Feed Codes too. Along with tons of options.
For Back plotting existing code I can configure this software to change Tools at the tool changes and show the proper tool in my graphic displays. This feature alone really helps me explain things to the young engineers and programmers I deal with daily.
Give it a try, I think you will like it.
C Ya
Mohawk