Why dont you just focus your panzers in the east for a blitz attack on Lithuania? Would easily make it possible to pocket those huge russian stacks on the northern part of this front and cost you almost no manpower to pull it off. Imho you should not let your Kriegsmarine rest, but try destroy the russian navy in the baltic. Your CAG can port bomb the russian ships in Leningrad and if they should decide to leave the port, they'll be doomed anyway. Would also make it possible to start an amphibious assault on Leningrad later, which would help the finnish army immensely, so they would not have to leave forces there and could be stronger on any other front.