$z matches 1 more \w than ': eg, >B< or >``Es`KI`B<, etc. Except for those ```S's, this generally results in a slightly shorter (different) line. Changing the 'p' handling to:

   |`i($z)     (?{$R++,$q=6})|`p($z)              (?{$X=$R;$R=0;$q=7})
 . . .

   :($15, (chr 120-$X), $bind{$17}, "")[$q-6];
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will let you print (selectively) at the bottom of the loop. (or get ready to do a lot of speed-reading:) eg,      ++$xx; $q==7 and print "$xx: (", length(), ') ', substr $_,0,80;

update: Oh yes, somes stats from the output:

  5801 substitutions
  longest line: 1095 chars (after 29 substitutions)
  first letter at: 456th sub (length 943)
  first  word:  456 to  525
  second word: 1314 to 1888
  third  word: 2813 to 3116
  last   word: 4125 to 4705 (length 71!)
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p