I'm a big fan of Mail::Audit, so my way to accomplish this would be something like (untested)

use Mail::Audit;

# read message from STDIN
my $mail = Mail::Audit->new();

$mail->delete_header("Message-ID");
# set To: header if you want to
# (not necessary for resend(),  just for the look of it)
$mail->replace_header("To", "Some Guy <someone@somewhere.com>"); 
$mail->resend("someone@somewhere.com");
[download]

Note that your MTA might add a new Message-ID for you if you don't specify one. This is beyond Mail::Audit's control.