mk3 ibiza

Hi everyone, got a mk3 Ibiza 1.9tdi 90hp with no ABS, just ordered a set of V-Maxx 4Pot 330MM 4x100 BBK. But I'm runing into a problem that my stock master cylinder, I think piston size is 22.2MM, might not be enough to pump these brakes. Stock the car comes with 1 pot 256mm in front and drum...