#!/usr/bin/perl is the standard place for Perl as declared by Larry himself. Even if you install /usr/local/bin/perl, please also put a link in /usr/bin and please use #!/usr/bin/perl in scripts that you make public
Please consider in the *nix world of today, you may make your system useless if you do the above. Changing the default system "perl" is quite dangerous. 5 years ago, I would agree, but today it's better to link the other way around if you're not installing a different Perl. Just my 2 cents.
"Well done is better than well said." - Benjamin Franklin