No problem, the hard work is done already. GM-1 is no issue either, if you need one with it in the future I'll make one with it.
Was the G-6 actually any heavier than G-2/4 when you think of the actual aircraft and not the armament? CFS3 is smart enough to calculate the weight of the guns and ammunition into the flying weight.
Calculated with the same aircraft, 300 rounds, kilograms converted into pounds from weaponry XML values by the divider of 0.4536. The "starting weights" are from the game itself.
MG131:
6355lbs for full ammunition and no fuel, minus 138.6lbs for the machine gun ammunition, minus 74.85lbs for the machine guns, minus 92.4lbs for the cannon, minus 92.2lbs for the cannon ammunition = 5957lbs for the empty aircraft.
MG17:
6231lbs for full ammunition and no fuel, minus 40.1lbs for the machine gun ammunition, minus 55.1lbs for the machine guns, minus 92.4lbs for the cannon, minus 92.2lbs for the cannon ammunition = 5951lbs for the empty aircraft.
Now, I had the empty weight set at 5893lbs so there's about 60 extra pounds in both examples but for all we know it might be CFS3 using a different conversion value between pounds and kilograms. Actually scratch that theory, I'm calculating it...
MG131:
2871kg for full ammunition and no fuel, minus 62.886kg for the machine gun ammunition, minus 33.952kg for the machine guns, minus 41.9005kg for the cannon, minus 41.811kg for the cannon ammunition = 2690.4505kg for the empty aircraft.
MG17:
2826kg for full ammunition and no fuel, minus 18.198kg for the machine gun ammunition, minus 24.9774kg for the machine guns, minus 41.9005kg for the cannon, minus 41.811kg for the cannon ammunition = 2699.1131kg for the empty aircraft.
The bottom line, something in these figures doesn't quite match (I'm still suspecting less than accurate conversions) but what does match is the relative weight of the different ammunition options compared to each other. If, and I'm not sure if it is the case, the G-2/4 was structurally the same aircraft as the G-6 you don't need a new flight model at all - changing the guns will take care of the weight difference. If it wasn't I'll naturally tweak the weight a bit.
*disclaimer: this took an hour and a half to write and the "Submit Reply" button was hit at 0005 hours, miscalculations are very possible*