I think I know what the solution is but I just cant seem to get it to work. Fusion360 has a post processor training guide and in it they discuss a section called polar interpolation, which is exactly what I need, it replaces one of the linear axis with a rotary axis and outputs strictly polar coordinates. If I go to prebuilt millturn posts such as haas 35st, doosan millturn, etc - and use that post to process my machine kinematics and toolpaths - it does output seemingly correct polar gcode. However, their post processors are significantly more complicated and have a variety of gcodes that are not relevant to linuxcnc. HOWEVER, when I try to manually integrate polar interpolation to the linuxcnc milling post, I am unable to get it to work, it still always outputs cartesian coordinates and or says the direction of my milling is incorrect.