The math is simple :) 4:3 x2 = 8:3 (2.66:1) 1:1 x2 = (2:1) 3:2 x2 = 6:2 = (3:1).
For 2.35 with a 2x anamorphic you would need something close to a 6:5 aspect ratio (12:5 = 2.4:1). If you want 2.35:1, using 4:3 and cropping a bit from the 2.66:1 image is most effective.
For 1.5x lenses just replace x2 by x1.5 - 3:2 would probably best, resulting in 4.5:2 = 2.25:1, needs a small crop for 2.35:1