Don't change to a B16 head, the B18C1 head has smaller combustion chamber (slightly) and same size valves so you'd actually be hurting yourself if you did that. If I understand you correctly you are using an OBD1 or earlier computer on an OBD2 block. Are you sure all your wiring is OK? It sounds electrical to me, if your head was leaking you would notice coolant or oil coming out. the fuel pump doesn't mix fuel, it just delivers it, I suppose it could be the problem as it is used to supplying a car with only about 100 wheel-hp now you are asking alot from it.

Don't bang on the Lude, it may be heavy but I've driven an SH, it's faster than people give it credit for. It's definitely faster than an Si which is supposed to be 15.2 or 15.1 not sure which. It was a LOT of fun, I'd trade my Civic up for one instantly.