You're not going to have time. Firstly you need the 4 injectors. Then you need someone with expert knowledge of removing & installing PD injectors as it is not a simple unbolt and plug in job. You need to have all the correct bolt torque ratings, and each injector needs setting up on a certain point of the cam rotation (This is where you mentioning the vernier gauge comes in). It's not easy at all. If you get it mapped on the current injectors, see if you can ask them to write you a map for higher fuelling injectors at the same time? They might do it for no extra charge.