I just draw it out on paper. mark 600 inches, and 1030 inches forward of the nose, or whatever the datum (zero point) is. Put the C of G wherever you want, say at 700 inches. Move 285,000 lbs for 2.3 inches, is the same as 1524 lbs for 430 inches (285,000 * 2.3 = 1524 * 430)
Course, I could be wrong. I'd feel better if someone chimed in and agreed