The problem that you were getting with a smaller size of file system or
something confusing about the newfs options was possibly due to the wrong
type of disk drive you've chosen when creating the file system via "newfs".
We don't know what option(s) of "newfs" syntax you specified. We are not
sure if you have the right size of file system (with 287MB) after you chose
160SC disk type.
You should choose a drive type which is closer to your drive specification,
or you could create a new entry with the drive physical characteristics
(number of sectors/track, number of tracks/cylinder, and the number of
cylinders/disk) in /etc/disktab for the particular disk drive. "newfs"
reads the information from /dev/disktab for a particular drive type and
invokes the /etc/fs/ufs/mkfs program to make a file system for a partition.