Some good info here, however,
FB25 has an engine mount connecting the engine to the lower radiator support. EJ25 cars dont have a provision for this mount.
Other concern, its highly unlikely that the gauge cluster and the BIU from FB car will be plug and play for the harness in the EJ car.
Next, the VIN number is stored in the ECU. when ECU is swapped and the car is scanned when being smogged, the VIN will not match. You will need to edit the EPROM in that ECU. I've done model year 2005, but unsure is the next gen ECUs use the same code.