I did my "Good" RD6 that way Grant, just filled the clutch compartments up as full as I could with the citric acid and the tranny top still on, and had a small fish tank pump running 24/7 for about 3 weeks, I had the steering clutch levers tied back as hard as I could too with rope, just to try and get some acid inside the pack, you have nothing to lose.
Good luck
Mike