I'm no expert in 323, but will tell you what I think. Your voltages, if taken with engine running, sound very low to me. I would expect 14v on a running system.

If the '94 alternator will match the other year mounting bolt holes, and the belt pulley is right, and you can hook up to the harness... it should work just fine.

Just for comparative users info, one old '70 4x4 came with an alternator and an external voltage regulator. As years went by, he could not buy a replacement alternator & regulator that would give enough voltage to keep the battery up.... only 13 volts or so. So he looked for a more modern replacement.... and discovered that the alternator for a '89 Mazda 323 was a bolt-up replacement. Luckily the v-belt pulley was located correctly also. The electric hook-up was straight forward, since the regulator is inside the alternator. This thing is still working today ... years after the conversion. I tell this story just to make the point that the modern alternator is a stand alone, self-sufficient device.... all ya gotta do is hook it up and spin it.

Its possible tha you have drain voltage too.

Check it and tell us news.