One thing that might make this more clear (as well as more generally customizable) is to separate the theme changes from the main script.
Build a configuration file, then read it into the hash. The key will be the string-to-find and the value will be the replacement. Then you can do something as simple as this:
foreach my $find (keys %chunks) {
$data =~ s/$find/$chunks{$find}/g;
}
You don't have anything complicated like backtracking or grouping, so it works. It's a bit slower than the other way, but the added convenience (and code beautification) might be worth it.
