The "4W" is actually "LW" and is the serial suffix. It's typically stamped on a second line and is often missed when recording the number.
As bronco45 mentioned, there were two different gripframes - full length and short. Your friends gun dates to around 1957 and will have a full length grip frame.
"Coltwood" plastic grips would fit your friends gun, but were supplied on earlier guns (1950 to the mid-50's).
Cobras made from the mid-50's to the mid-60's still had the full length grip frame, but were supplied with wood grips with silver Colt medallions. These are the ones you friend should look for. This is the only photo I have, but it should give him some idea what to look for.
First series Cobras made from the mid-60's to 1973 (when the shrouded ejector rod second series was released) had wrap around grips like these.