Thanks Vipermad,
I did get the script to work however, there were a few differences.
Where I had to look for this in ubbmisc.cgi
I couldn't find it at all. I found two occurrences of this:
And placed this underneath at both occurrences:
I then went to the General Setting in the control panel and set the character limit. I know it wont change any of the character limits in the existing sig's, but it works for new members and existing members updating their profile.
Thanks...