I copied the "edlabel" from the base (pre-Sunday base.tar.gz)
that I had on the SunOS labelled disk to my NFS mounted area.
  I then played with things:

# /sbin/edlabel /dev/rsd0c
edlabel menu:
print   - display the current disk label
modify  - prompt for changes to the label
write   - write the new label to disk
quit    - terminate program
edlabel> p
        type_num: 4
        sub_type: 0
       type_name: SCSI disk
       pack_name: Sun1.0G cyl 1703
    bytes/sector: 512
   sectors/track: 80
 tracks/cylinder: 15
       cylinders: 1703
sectors/cylinder: 1200
partition a start cyl=      0,  nblks=    600000 (500/0/0)
partition b start cyl=    500,  nblks=     96000 (80/0/0)
partition c start cyl=      0,  nblks=   2043600 (1703/0/0)
partition d start cyl=      0,  nblks=         0 (0/0/0)
partition e start cyl=    580,  nblks=   1347600 (1123/0/0)
partition f start cyl=      0,  nblks=         0 (0/0/0)
partition g start cyl=      0,  nblks=         0 (0/0/0)
partition h start cyl=      0,  nblks=         0 (0/0/0)
edlabel> m
modify subcommands:
 @   : modify disk parameters
 a-h : modify partition
 q   : quit this subcommand
edlabel/modify> @
        type_num: 4 ? 
        sub_type: 0 ? 
       type_name: SCSI disk ? 
       pack_name: Sun1.0G cyl 1703 ? CFP1060S
    bytes/sector: 512 ? 
   sectors/track: 80 ? 94
 tracks/cylinder: 15 ? 8
       cylinders: 1703 ? 2756
sectors/cylinder: 1200 ? 
edlabel/modify> a
partition a start cyl=      0,  nblks=    600000 (797/6/92)
partition a start cyl: 0
length as <nblks> or <cyls/trks/sects> : 797/0/0
edlabel/modify> b
partition b start cyl=    500,  nblks=     96000 (127/5/26)
partition b start cyl: 797
length as <nblks> or <cyls/trks/sects> : 127/0/0
edlabel/modify> c
partition c start cyl=      0,  nblks=   2043600 (2717/4/40)
partition c start cyl: 0
length as <nblks> or <cyls/trks/sects> : 2756/0/0
edlabel/modify> e
partition e start cyl=    580,  nblks=   1347600 (1792/0/16)
partition e start cyl: 924
length as <nblks> or <cyls/trks/sects> : 1832/0/0
edlabel/modify> q
edlabel> p
        type_num: 4
        sub_type: 0
       type_name: SCSI disk
       pack_name: CFP1060S
    bytes/sector: 512
   sectors/track: 94
 tracks/cylinder: 8
       cylinders: 2756
sectors/cylinder: 1200
partition a start cyl=      0,  nblks=    599344 (797/0/0)
partition b start cyl=    797,  nblks=     95504 (127/0/0)
partition c start cyl=      0,  nblks=   2072512 (2756/0/0)
partition d start cyl=      0,  nblks=         0 (0/0/0)
partition e start cyl=    924,  nblks=   1377664 (1832/0/0)
partition f start cyl=      0,  nblks=         0 (0/0/0)
partition g start cyl=      0,  nblks=         0 (0/0/0)
partition h start cyl=      0,  nblks=         0 (0/0/0)
edlabel> ?
Invalid command.  edlabel menu:
print   - display the current disk label
modify  - prompt for changes to the label
write   - write the new label to disk
quit    - terminate program
edlabel> w
ioctl DIOCWDINFO: Invalid argument
edlabel>