MTQ or united fuel in WA will both be able to supply upgrade kits for what you want. The td42t are all ole school mate right to 06 just a boost compensated mechanical pump (in my opinion compensator is the engines own worst enemy) With the setup you are talking about shouldnt see a problem with reaching those figures.
Dont be to surprised if the prices of the 4.2 doesnt come down for a while too. With the Y62 only coming out with a single petrol combo i think they will hold their value for a while.