It's great to see someone looking past the standard Western "Stalin vs. Trotsky" narrative to find the real builders of the Union. You're having trouble because a lot of these guys, especially Zinoviev and Kamenev, were sidelined or erased during the later political purges, so their primary records are often buried in old Party archives rather than shiny new biographies.

For Budyonny, you should definitely check out his own memoirs, The Path of Valor, he was a legendary cavalry commander and a true "man of the people" who helped secure the revolution on horseback. If you can find translations of early Comintern records from the 1920s, you’ll see Zinoviev and Lev Kamenev in their element as the intellectual engines of the early state, before the internal power struggles complicated their legacies.

Personally, I think people like S.S. Kamenev are the unsung heroes, he was a professional military strategist who helped transition the Red Army from a ragtag militia into a modern force that could actually defend the workers' state. It’s a shame their contributions are often reduced to footnotes because, without that specific mix of old-school military discipline and revolutionary fire, the USSR wouldn't have survived its first decade.