!984 Nissan King Cab

I have an 84 king cab 4 speed manual transmission that has been sitting up for a while. Have been going through it trying to get it running. Finally got engine running good, only has 81000 actual miles on it, but the clutch will not operate. I can see the slave cylindar moving the disconnect arm underneath but it does not release. I can put it in gear with the engine not running but not while the engine is running. I have completely drained the master and slave cylinders and have all fresh fluid and they have been bled. Any thoughts. Thanks