If you are talking about the last bjt, emitter follower indeed, I wouldn't go above 10k unless I wanted to purposefully introduce "cathode follower"-ish distortion.
FWIW I breadboarded the 3-stage version of this circuit, not the 4-stage one, and there was plenty of gain and still some wiggle room to push it with a TS without turning into white noise. YMMV![Smiley :)](https://www.ssguitar.com/Smileys/default/smiley.gif)
Oh, and ref. biasing, nothing wrong with using 2 resistors in series to get to the right bias either.
FWIW I breadboarded the 3-stage version of this circuit, not the 4-stage one, and there was plenty of gain and still some wiggle room to push it with a TS without turning into white noise. YMMV
![Smiley :)](https://www.ssguitar.com/Smileys/default/smiley.gif)
Oh, and ref. biasing, nothing wrong with using 2 resistors in series to get to the right bias either.