Quite a while ago, maybe already ten years or so, I had a brief e-mail conversation with Martin Andernson where he mentioned his general interest in a cycle devoted to Peiko's orchestral works, however he also wrote that as always, it was a question of getting it financed. I am afraid things will not have changed meanwhile. Nevertheless, there might be some hope: Toccata have released a number of Soviet rarities in the past years, includig Peiko's piano music of course, but also some orchestral works by Shebalin, Weinberg and others, and they seem to be cooperating with Yuri Abdokov (who has been in charge of the liner notes for their latest Galynin CD, for instance), a pupil of Peiko and Boris Tchaikovsky. We will see.
Mosolov's "Antireligious Symphony" (a piece of 30 minutes with chorus, also labeled symphonic poem) has only recently been found in the archives of Soviet radio, it has been performed and apparently also recorded for the radio. Some information can be found here:
https://www.deutschlandfunk.de/russland-urauffuehrungen-des-komponisten-mossolow-sorgen.1993.de.html?dram:article_id=397308A German article (if necessary, I can provide some details).
As for Robert's suggestions, I should think about my own preferences in more detail. I would certainly also nominate some composers from the republics, i.e. Central Asia and the Caucasus region. As for Levitin, I only recently found out that there has been a 2 LP set with two of his symphonies by Melodiya. I already told Mike Herman and it now appears in his online catalogue (however, it mislabels the unnumbered "Days of War" Symphony as No. 1). Unfortunately, these LPs seem totally elusive.