After I published the post on design decisions for MTKS / Buran, I received a message from Vadim Lukashevich. If you are not familiar with his work, he is the author of “Cosmic Wings”, the definitive book on spaceplanes.
He has written a comprehensive post on the OS-120, which puts everything into context. You will find it here in Russian:
http://www.buran.ru/htm/os-120.htm
And an English translated version here:
https://www-buran-ru.translate.goog/htm/os-120.htm
The whole site is well worth your time to explore in depth, and it is beautifully illustrated.
Here’s my original post.