if its a 6cyl hq to hz van which i think i read a thread on you buying it then its simple..radiator and hoses need to be from hq to hz v8..motor can be from hq to wb for a straight bolt in..if its from a commodore then you need to change sump and pick up and engine mount brackets and water pump and front pulleys...
in relation to the motor you will need an aus 4 speed bolt pattern or trimatic pattern if you are running a 4 speed manual..turbo pattern is different bolt ups for bellhousing..6 cyl speedo cable and x member are the same if doing tri or 4 speed conversion..
you will need a large 10 bolt diff from a v8 hq to wb van ute or tonner and you will need a v8 tailshat from a wagon,statesman ue,van to match the diff..if you have a tonner diff you will need a step down uni for the shaft..its a very simple conversion if you are mechanical,which i believe from other posts you are....just watch the turbo pattern block thing and its easy..