There was still a lot of Finnic population around Karelia, Ingria and assorted places before Stalin did his 'thing' so I don't think that it would be a stretch for Finland to have cores on Ingria. After a time of integration, of course. Claims are perfectly fine in the end, though.
I see that you wrote you think Scandinavia is fine currently, but maybe there could be the possibility for Finland to assert claims on at the Swedish portion of Torne Valley? I'm thinking the provinces: Kalix, Karesuando, Gällivare, Luleå and Kiruna at maximum extent. I'm not expecting you to of course do any of these things I've outlined, but I thought I'd just post some ideas. It's your mod after all.
And if not Kalmar, then Danmark-Sverige also sounds incredibly sexy.
I hope you post the timeline eventually.