The different series turbos (not cars) cannot be mixed "directly" without some machining or spacers being used.
If the series has the same turbine wheel and CHRA ie Ball bearing then the prim<-->secondary can occur.
Series 1
VF14 -//-> to any primary (with maching can be made fit to any primary turbo as it has the 5700 turbine wheel)
VF17,VF19,VF21 <--->VF13,VF16,VF18,VF20
Series 2
VF27 -//-> to any primary (with machining then best fit to a VF25 or VF26 as these use the same 6200 turbine wheel)
Series 3
VF32 <-->VF31 (with maching then can be made fit to any primary turbo as it has the 4700 turbine wheel))