You may just need to add a G17 before the G98 line. Assuming you're using a 90deg live tool. G17 for XY plane and G18 for XZ plane I think. Something like this...
( OPERATION 3, MILL CONTOUR )
( TOOL POSITION 1, .5 DIA. ROUGH ENDMILL )
( 90DEG HOLDER--YG X-POWER 1/2" ROUGHING STUB ENDMILL )
N4
G54
G30U0.V0.W0.
G0G54G28B0.
G0T0102
M45
G0G28H0.
G0C0.
G97S1910M13
G17U0.V0.
G0G98Z.11C0.M8
X6.8279
Y.0794
M68
M98P120
M69
G0X6.8279Y.0794C-180.
M68
M98P120
M69