Siberia is great, because the low dev is a good thing, as it means you get tons of fur and iron manufactories for basically no GC cost. Once build up it's at least 100 monthly from trade and production, and even before that point you will get a sizeable trade income from it with little investment required. The artic provinces reduce the value a bit, but most of it isn't actually artic provinces so you can still build Manufactory + workshop. Plus the extra merchant.
And as Russia, you basically get it for free except for maybe a couple wars against the hordes. So it's not like going into Siberia prevent you from taking Persia in any way.
The best is I think to state a few good states (especially those that get gems) so that they get the good produced modifier from the TC. It's not like it cost a lot of GC to state 3 devs land.