In no particular order, beyond what has been said: SCSI number doesn't really matter in a CII (jumperless should be 0), but set it by jumper if you wish to 1 or 2; set it to auto-spin and with termination on; be prepared for needing Silverlining or the like to partition, though standard System 7 tools may work on the drive; the power requirements of a fast drive like this may press the electrics of an ageing CII hard, so a recap of the analog/ power board is advisable; and obviously you will need a 68-pin to 50-pin converter. Say a prayer, shove it in, and give it a whirl.
I wouldn't install anything beyond 7.1 on a CII, by the way.