It’s a little light on infantry. I try to buy at least as many inf as other units. Some buys I’ve tried in the past:
1fgt, 1tnk, 3inf-My personal favorite.
1tnk, 1art, 5inf-Good choice if you’ve moved a lot of Inf east to counter Japan.
3tnk, 3inf-Not bad, if you still have your original tanks it makes for a good Armored force.
3art, 4inf-good for defense and trading dead zones.
I rarely go for an all infantry buy, since russia is short on offensive punch to begin with.