for my $i (0..(@keys_raw > @keys_ref ? $#keys_raw : $#keys_ref)) {
  my ($key_raw, $key_ref) = ($keys_raw[$i], $keys_ref[$i]);
  my ($val_raw, $val_ref) = ($raw58{$key_raw}, $ref58{$key_ref});
  #... if-block as before
}