As I understand best possibility for big salamon over 30 pounds is Kola River.
The season opens in June and the entire month is dominated by the fresh run of the multi-sea-wintered fish averaging between 17lbs – 30lbs, with some monsters in excess of 40lbs.
Recommended operator? Cheaper than other rivers since not any helikopter transport?
Unfortunately Kola River is not in the wilderness .You have train,cars nearby and as I heard one of the most polluted area in world.May be disposable for poaching ?