Would he consider Polish PCs? If so, Zelenski, Zarzycki, Rozycki (2), Maliszewski (especially) - all, I think, available from PWM. There are concertos by Nikolai Strelnikov, and Sergei Vasilenko which I believe are supposed to be attractive. I think Igor Markevich wrote one. Then, of course, there is Felix Borowski (NOT Russian, I know, even though he sounds it - but a lovely concerto) - and one ought not to forget the 2 by Eduard Schutt, who was of Russian extraction.