You would need 2 PoDs to properly butterfly as much as Russia, rather than crushing it when it already appeared.
Weaken Byzantium as much as possible, and make Umayyads and Abassids clearly win the Khazar Wars. You don't need to crush them (I don't think it would be that possible) but to make them convert definitly to Islam (it began OTL, but discontinitly).
Weakening ERE would probably ask for more successful Bulgars on Balkans and Arabs on Anatolia, but everything could be fine as long that Black Sea isn't firmly controled by the empire, and that someone other than them build a fleet on it.
It would be then possible to nerf the Crimea/Kiev/Novgorod trade road at the benefit of Caspian/Volga/Ladoga, that was favoured by Arabo-Muslims merchants. While the influence of Varangians would probably create a Slavo-Finn-Norse ensemble corresponding roughly to OTL Republic of Novgorod, as well influencing south, if Constantinople is less interesting as a diplomatic and/or trade center, and with a Muslim Khazaria and V.Bulgaria, you have more chance to favour their expansion or influence to create a Slavo-Muslim ensemble (if not an expension of Arab trade road states and khanates) and to butterfly Russia as a whole (except to the North, but it wouldn't be Kievan Rus')