Right. My math skills are insufficient to come up with a formula for this, especially since the triangle in question isn't quite a right triangle. One could work it out numerically but I don't know the lengths of the other two sides. Just guessing, I would say that if you add 1" of lift you'll have to lengthen the LCAs by about 1/2". That sounds like it's probably within your range of adjustment but maybe just barely?
Of course as you know, for such a large lift you'll also have to adjust the upper arms to get the driveshaft pinion angles back within spec. And that will change how much the LCAs have to adjust.
IIRC, the EVO 2.5" lift comes with instructions about how long to make each arm. Maybe Mel will do the math and publish a chart saying exactly how long each arm should be for any given lift