And Kodak has a huge number of datasheets online - its just that the volume makes it hard to find the one you want.
Most of the most valuable ones are found through this link: http://www.kodak.com/global/en/profe...ankIndex.jhtml
The most useful one for your purposes is probably this one: http://www.kodak.com/global/en/profe...3cf/e103cf.pdf
That table is found under the "Chemicals" sub-link on the first page I linked to.
If you want a powder developer that will develop 60 rolls of film from a single package, buy a 5 litre package of Kodak X-Tol, mix it up and split the five litres into five 1 litre bottles.
Use one of the bottles as your working solution, and the other 4 litres in a simple replenishment regime (70 ml per film).
It should last longer than the projected 6 months, but even if you decide to toss what remains after 6 months, it will still work out to be very economical.
I would suggest, however, that you include two packages in your initial order - you will save on shipping.