the 22RE setup would be very easy to wire up and replace the 18RGEU setup. the ECU's are vitually the same anyways. only control fuel not fuel & timing. simple analog ecu's.
plus the parts would be very easy to souce.. hth
or if that fails the 2s-e is a good donor. These computers are only good though if you run a pretty much stock engine. If your working it or boosting it id suggest going after market.