I bought a bunch of dual vertical 30 pin sockets from, IIRC, Jameco when they were closing them out. They are also spaced too close together, but they are relatively easy to cut apart and use individually. I use a small bench vise to hold them and a cutting wheel on a dremel to do the cutting.
While a dual socket might provide some superior lateral stability, the cut-apart individual sockets do still have the strain relieving plastic pegs.
Not strictly true. The 80 pin drives are wide devices. The Mac has a narrow SCSI bus. Even though the upper (wide) bits aren't being used, they should be terminated on the drive. So just putting the drive bare in the middle of a properly terminated SCSI chain might work, but it is not proper SCSI configuration. The upper bits on the wide drive must be terminated, unless it is in the middle of a wide SCSI chain.