First of all, the mods on the bottom row are 1.5, 1.25, 1.5.
The AEKII in ANSI has otherwise a standard layout, just like the full-size PC keyboards, with a width of 15u.
The AEKII in ISO, however, is also 15u wide but the rightmost keys 0(except for the bottom row) are 0.25 thinner and the leftmost keys are 0.25 wider.
So, the Backspace and Tab keys are both 1.75 wide. The Shift keys are 1.5 and 2.5 wide.