If you use a Skunk2 manifold, OBD1 P30 is the way to go, just richen up the fuel a little with an adjsutable fuel pressure regulator to account for the extra .2 displacement of the 1.8L over the B16a. You basically have a "poor man's ITR" at this point.
If you stick with the GSR "snail" dual runner intake manifold with butterfly secondaries, then get an OBD1 P72. This ECU will open the butterflies, and adjsut fuel accordingly with the extra airflow.
ECU's in Honda's are 99% IDENTICAL besides pin outs, and the program on the chip. If you compare a 99 GSR ECU to a 99 Civic DX, they LOOK identical, PROCESS identical, but have different sensor expectations and signal outputs.
Let me know if you guys need any more info on the subject.