You don't have to be afraid of the compression much. The phase1 motors of that year you pulled has a compression ratio of 9.5:1. The EJ22E heads of that motor is 40cc. Your WRX heads being 49cc drops the compression a good bunch. The JDM WRX's run 9.0:1CR.
You would just need a retune because of the higher compression. Run your same timing curve, but maybe lower boost 2-3psi. Only thing I worry about is the engine bearing's condition of that old of a motor. I replaced my 170K mile EJ22T bearings with new ones.