During the 1960's could the Official Scorer in a MLB game decide who the winning pitcher was if he pitched 7 or 8 innings and left with the game with the score tied 1-1 if his team later scored the winning run in the 9th inning? I know this is not the case now, but thought it was back in the 1960's.
I don't have access to a rulebook of that era, but I've not heard of this before.
Baseball Almanac has a page listing major rule changes over the years. As this seems quite "major" to me, I'd expect it to appear there. I see several mentions of changes to the save rule, but not for wins and losses.
A copy of a relevant rulebook would be best, but short of that I'm leaning to "no, there doesn't seem to have been a change in this rule since the '60s"