The best results come from testing for yourself. Get a step wedge. It will do more for calibrating all sorts of your photogrpahy than you can imagine.
I work with out of date paper all of the time. I calibrate every new box or envelope, typically using less than a piece of 8x10 to make a whole bunch of 2x2.5" prints of a projected 6x6cm 31 step step wedge.
The prints are exposed starting at all yellow, then 15 units less Y, unitl zero, then start dialling in magenta. Write the filtration on the back in pencil.
You end up with about 12 prints. I develop them all together for the same 2' in a dektol like developer 1:2 dilution. That is my standard print developer arrangement.
Then once dry you count the number of steps between just barely off white to just not quite full black.
You can refine this more to figure out what amount of Y+M+C gives a 1/3 of a step reduction in exposure. For my case it is 7cc.
You can then go back and plot what the response is raw, and then adjust to dial in some magenta with your yellow to give equal time exposure for just off white, or some other value of grey.
If you are interested, pm me. I got this method off this site about 6-7 years ago from an old post from 'noseoil'. I can pdf the print out and mial it over or post it here.
A variation of this technique is also discussed in 'the varable contrast printing manual' or something like that by Anschell.
