@KenSmith - I think the confusing point here is even if you get a post processor to produce G2/G3 (arcs), the underlying software controlling the machine (grbl) does not support true arcs. Arcs will be turned into small line segments using $12 tolerance.
I’ve been using the “Open Hardware Desktop CNC” post processor with Fusion recently and it seems to generates arcs (though you can set the minimum chord length). However, I have had UGS return errors (assuming they are from grbl) saying the machine does not understand an arc command. It didn’t seem to affect the outcome, but not reassuring having the machine pause for no reason in the middle of an op. I have a screen shot on another computer I can upload for the curious souls.
-Tom