Please note the above texts may not be 100% correct because of information leak.
I'll try to edit them as I get the correct info.
And by the way, if someone has an access to old Autocar magazine issues, there might have been a note or an article about Soviet race in 1961, as in November 1961 Autocar journalist has seemingly visited the race (it appears to be the race on November 12, 1961 in Luzhniki, Moscow), as written in one of the books...