I haven't looked it up, but I think the league you're referring to was the Pacific Coast Hockey League (PCHL). I think the WHL was pretty much always a junior league because teams like the Edmonton Oil Kings, Saskatoon Blades, Regina St. Pats all have a long history of junior hockey, not pro.
As well, the International Hockey League (IHL) was the main rival to the NHL for decades, even though many of the teams had farm affiliations with the NHL. The I just never had the deep pockets to pay players top dollar. Through the 50's, 60's and 70's, the only things the NHL had going for them were some of the best players in the world, a monopolistic stranglehold on the biggest markets in the East, and HNIC. Those three things protected them from the plethora of pro leagues all over the continent.
Edit: it would appear we are talking about the same league as the WHL grew out of a merger with the PCHL.
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