s/(.*ing)(?:(?!bob|fred|bill).)*(more)/\1HIT\2/;

##</code><code>##

s/
   (.*ing)
   (?:
      .{0,2}
      |
      (?!bob).{3}
      |
      (?!fred|bill).{4}
      |
      .{5,}
   )
   (more)
/\1HIT\2/x;

##</code><code>##

my %bad_words = map { $_ => 1 } qw( bob fred bill );

s/
   (.*ing)
   (.*)
   (?(?{ $bad_words{$2} })\A(?!\A))
   (more)
/\1HIT\3/x;

##</code><code>##

s/(.*ing)(?!bob|fred|bill).*(more)/\1HIT\2/;