Depends on what you want mate, IDI, TDi or PD TDi
IDI 1.9's then you have the AAZ
TDi's then you have more to go with, like an AFN, they can be converted to use a mechanical pump for simplistity by using an AAZ pump thats been reworked or using something off a Land Rover 300TDi or similar.
PD TDi, then wiring becomes tricky and you'll also need the accelerator pedal from a PD vehicle to graft into your car....
all said and done, If you haven't already spent a load of money on the car you've got or you can't buy your car with the engine you want to put in, then just buy a polo with the engine you want already in it...