I just did an iron treatment to my 10,000 SWG pool last Friday and Saturday with 1.75 lbs of AA and 32 oz of Jack's Magic The Purple Stuff.
It took approximately 60 ppm of liquid chlorine to get it to hold at a FC of 4. I checked, every half hour and then later hourly all day Saturday before it would hold at 4 FC, adding acid as necessary to keep it 7.2. At no time did I allow the the chlorine to above 5. This is in a pool with a CYA of 40.
I think the 2.5 ratio might be good for citric acid, I am no chemist so I am guessing here, but you would need to take into account the ascorbic acid demand that I experienced.
So it seems from experience with AA only and 32 oz of Jack's Magic The Purple Stuff, I know nothing of chemistry, that about 30 - 34 ppm of chlorine will neutralize 1lb of AA in a 10,000 gallon pool.
It would be interesting to know what you actually end up using and if it correlates with my experience. If my experiece is correct you would need 60 to 68 ppm of chlorine just to neutralise the AA plus extra for the Citic Acid.
Let us all know the final tally so you may help others.
Hope this helps.