from experience with helping get the speed3 sedan running yu will need a lot of electrical. first big issue would be dealing with a pcm and if the pcm has to be changed then yu WILL HAVE to change the pbj to a gem.
those would be your biggest issue.

im not fimiliar enought to say that yes a 2.5 will run off 2.3 pcm.
from the speed i no the issue would be with timing, crank sensor and the reluctor wheel on the pulley.
the crank will control spark. so wrong set up = no spark.

if you out the 2.5 i would put the 6spd manual instead of the 5spd.
only thing would be checking cv shafts. one may be longer or shorter from gen1 to gen2

if anyone else has ideas or can confirm anything ive said.
im sure i can check pt# and answer a few questions.