I thought that sounded familiar. Your link goes to a design called the NS-1 by Nat Stinnette W4AYV. The link takes us to a Feb 1975 version in Ham Radio. It appears he later deleted the input 741 amplifier & wrote that the PLL alone was so sensitive that it wasn't needed. So, it went to a 2 chip board (NE565 PLL & 741 comparitor). I'd ordered one of his boards back then to build mine.
If you were to work up a PC board for this, I would be interested in that. I have a use for a simple TU that will only be fed clean AFSK inputs.
FWIW, I also had made up a PC board layout for the Eric Volpe demodulator that used the XR2211. I extended some of the traces & lands to accommodate parts with slightly wider lead spacings. Should have also changed the connector lands. I had a few boards made & have tested one but only briefly.
Here's more links to Nat's NS-1.
NS-1 demodulator first appeared in RTTY Journal, October, 1974
https://www.navy-radio.com/manuals/tty/rtty-journal/1973-1977/PDF/VO22NO8.PDF
NS-1 PLL Update. RTTY Journal, Jan 1976, pg3
https://navy-radio.com/manuals/tty/rtty-journal/1973-1977/PDF/VO24NO1.PDF
Active Bandpass Filter for RTTY, for use with NS-1 loop demod
https://www.worldradiohistory.com/Archive-DX/Ham%20Radio/70s/Ham-Radio-197904.pdf
Update on the phase-locked loop RTTY demodulator," Ham. Radio, Aug 1976
Wayne
WB4OGM