Actually, the 2 game total point final was alive as late as '86. Instead of a crossover the rule was that if the 4th place team in one division had a better record than the 3rd place team in the other then the division with only 2 teams played a 2 game series while in the other division 1 played vs. 4 and 2 vs. 3.
I watched the last game of the '72 2 game total point series through a hole in the Ivor Wynne fence. That was, I believe, the last series like that.
The WIFU (Western Interprovincial Football Union) also had the 2 game total point approach for years until the early 60's.
When the IRFU (Interprovincial Rugby Football Union) became the Eastern Conference of the CFL in '61? it kept the 2 game total point from the IRFU but I believe that a series early in the 50's was tied after 2 games and instead of going into overtime (which they had no rules for) the league officials decided to add a 3rd game!
The partial interlocking schedule only ended in 1980 because that's when the two conferences officially merged completely.
It took a LONG time to get a united CFL. I don't even know if the CFL has legal title to the Grey Cup even though only WIFU and IRFU have played for it since the ORFU (Ontario Rugby Football Union) stopped challenging for it in the year that I was born- '54. Universities could challenge for it before that as well.