As above, buy a complete car.
Changing the engine from another vehicle will be a lot of work, including wiring looms, ECU, etc.
Front suspension will be stiffer for the diesel/van, so the whole front legs will need swapping, plus the brakes may be bigger. Then you have to tell DVLA and make sure that gets registered correctly, then tell the insurance company, who will then have to compute a new premium based on it being a special.
Do you want transport, or a project?