Pistons should be identical. The stroke is what makes the difference. For example, the Supertech pistons I have are 11:1 for a 2.3 but 10:1 for my 2.0. The crank/rods are what make the difference, although I'm not sure which or both.
'04 Mach 1. Built. Turbo. 667whp/631wtq
'06 Focus. Built. Turbo. WMI. (sold)
'03 Mach 1 : 12.61 @ 106.59 (sold)