I'll just add that bash and csh script language are different languages. So if a script was written using the bash language, do not try to interpret it using csh, and vice-versa.
Bottom line, is you definitely do not want to change that #! line at the top of the script.
If you're missing the bash or csh interpreter on your system, then that's what you should focus on.
Depending on which brand of Linux you run, the way to install it will be slightly different. Let us know.