blahblahblah ++ re use of a dictionary. Coupled with the regex in the OP (or, perhaps, one that's rather more specific and insistent on the presence of periods), you may have something of a start on that part of the problem.

It does seem to me that reflowing text (horizontally) around ascii art will be problematic, at best. Perhaps it would also be well to accept a less design-oriented target and accept leaving anything determined to be ascii art as an inline item (takeout box, dropin, for a couple of terms that may clarify my intent), with the reformatted text above and below.

test here yada ya da   0000 01 02 03 04...
ya da'in continues       0010 0f 0e 0d...

test here yada ya da

0000 01 02 03 04...
0010 0f 0e 0d...

ya da'ing continues

My next notion may be unmanageable, but might be worth exploring: Would creation of a second dictionary containing such common elements as the address fragments at the beginning of each line of a hex dump (2nd example) and the multiple spaces initiating each line in the BBS logo be worth the effort?

and <big grin> while use of a dictionary might not have returned this result; the mouthful of the title might have been reduced by using "reparagraphing"?