Well, if you need three drivers, I'd name the following:
1. Madis Laiv (Estonia, Tallinn) - six-time USSR champion (won F1 championship in 1971, Estonia 16M
) and the 1975 Cup of Peace and Friendship winner. He was known as 'the thinking driver' who could always combine high speed and reliability in his driving.
2. Vladimir Grekov (Russia, Krasnodar) - five-time USSR champion (won F1 championship in 1976, Estonia 18
). Grekov was a very talented driver who started racing single-seaters in 1966 and unexpectedly won the USSR championship the next year.
3. Viktor Schavelev (Russia, Moscow) - 1965 USSR F1 champion (Moskvich G4A
), a great 'universal' driver who also raced in rally (won three national championships) and winter track racing. I have the honour to be acquainted with him, and his biography, illustrated with the photos from his personal archive, is on my web site: http://www.ussr-auto.../schavelev.html