RomRaider

Hi,
I am in the midde of a swap from a JDM fxt crosssport to JDM FSTI and i am stuck with the ECU because of the immobiliser.
A little background.
Last year i had a problem with my engine and decided to just get another engine. I eventually ended up with an EJ257 Tomei rebuilt long block at a very attractive price and i took it.
However, the OEM ECU for this FXT is one of those headache ones that cant be read by the normal OBD2 methods. I however have constantly been bothered with using the old ECU since i dont want to ruin this almost new engine with an incompatible tune.
I was convinced that i can get it mapped to match but i wasnt just not happy with the results.
So i got a deal for a complete harness and ECU swap for an FSTI and decided to go for it.
With the wiring and ECU swap done, i discover the ECU has an immobiliser in it and i cant bipass it.
The old ECU (2G) is incompatible since it uses 5 plugs instead of 4 plugs on the 9U ECU.

What other compatible ECU can i use in place of the FSTI ECU to run this engine?