I bet you could use a ZX2 lower timing pulley. Its roughly the same size. If you buy any Zetec timing kit it comes with one, but is not used in the Focus.
04 ZX3 RIP [Best Non-SVT FITF12][3/13 ROTM][7/14 ROTM][2014 ROTY][Best Engineered FF14]
01 SE The V8 Estate [Organizers Choice FF15]
02 SE The SVTedan
12 SE Hatch Sport & Winter Package, ST Front End