Route question for everyone

I don't want to get fully ahead of myself -- still trying to find a way from Oslo all the way up north to Hammerfest (northermost city in the world. . .check). Taking a couple overnight trains tonight to get half way there. I think I can take local buses the rest of the way. But here is my question.

I have always figured I would find a way from there down to Helsinki, Finland, and then from there into Russia at St. Petersburg -- which I do want to hit. After doing a bit of research this morning though, it looks like I could go from Hammerfest to Murmansk, Russia. From there take a 30 hour train down to St. Pete.

Murmansk sounds kinda interesting to me. I think it was the main Soviet port on the Atlantic side during the Cold War, at least in summer. Not sure, but I thought I remember reading about it somewhere.

Should I skip Helsinki? Head back into a cheaper place that is a little more adventurous? Or see another country that I've never seen, Finland, although quickly?