Well, for what it's worth, up to 1973-74, the World Championships were sort of best-on-best minus Canada (a HUGE minus obviously) and USA (not a big hockey power pre-80s IMO). Around mid-70s, many of the best young Swedish players went to North America (B. Salming, U. Nilsson, Hedberg, Sjöberg, Roland Eriksson...), as well as some Finns (Ketola, Riihiranta, Hagman, Tamminen...), so it was only the Soviets and Czechs who had all - or nearly all in latter's case [Nedomansky & later P. Stastny defected] - the best players with them.
I would rank the European countries as follows (during the 70s):
USSR ([at least nearly] on par with Canada)
Czechoslovakia (a notch below both USSR and best of CAN but had the ability to beat both; world champions in 1972, 1976, 1977 [and 1985])
...
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Sweden (could beat the Czechs regularly, but rarely beat the Soviets. Usually the bronze medallists below USSR and CSSR)
...
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Finland (could beat the Swedes but rarely the Czechoslovaks and basically never the Soviets. Often struggled vs. clearly weaker teams. Big underachievers before the 1990s! Usually 4th but never got a medal prior to the 1988 Winter Olympics.
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The rest (East and West Germany, Poland...)
So - to answer your question - I guess no, there wasn't really best-on-best tournament [in which every notable hockey power participated] before the 1976 Canada Cup and even that didn't have all the best Soviet players... but because it was rather their decision not to send their best possible team, I think the 1st Canada Cup counts anyway.