Ebay headers only come with one o2 bung, mainly because they get installed in EFs and the likes, which only have one o2 sensor wired, then people get chipped ECUs to run only one O2 sensor.
The o2 sensors should be one upper and one lower for OBD1, for OBD0 there are two up top, but you only need one in the first place. Get a B16 header with an upper bung, order a chipped PM6 or PR4 and run one-wire using the AC relay (Unless you use AC, then you can have them chip your ECU for single O2.
Just trying to save you some pain-in-the-ass wiring, I'm currently piecing together a harness in my CRX for a similar setup to you. I'm running one O2.