[cryptonector]

Are endashes and emdashes part of English though?

In any case, yes, overstrike is just an approximation, but believe it or not, ASCII was designed to make it possible. And yes, it kinda sucks, and yes, it doesn't really make ASCII a multi-byte encoding, not exactly. But it's a funny thought that ASCII kinda almost was a multi-byte encoding. One can imagine ASCII evolving to treat BS<mark> as not unlike Unicode combining codepoints to make it possible to get proper diacritics even on capital letters, but ASCII would still have been a dead end, naturally.