VMBM
Hansel?!
YouTube footage also shows the quality of the opposition.
And it also shows how Firsov compares to his teammates, including "'70s players" like Kharlamov (already ranked in this project), Mikhailov, Maltsev, i.e. the footage from 1969-71... And it all looks pretty good for him imo, since he was WHC All-Star LW in 1969-71 over Kharlamov, for example.
Maybe at some point you can state the reasons why you think that Firsov would have struggled against NHL opposition more than, say, Kharlamov did (if that is your main problem with Firsov, that is).