They will 100% fit in JDM rail ... we did this in many JDM 2JZ engines but you need to install the injectors resistor box/pack because the US 550s are LOW impedance type whereas the JDM 440s are HIGH impedance type.are the stock US 550cc supra injectors straight bolt in to the JDM 2jz?are they both low impedence motors??
my car is a JDM aristo with the 2jz gte.so its running the stock aristo wireharnesswhat wire harness are you running?