I'm not sure why it is "my" math, as we are both speculating on what went on with Southern voters, but sure.
So, lets take a look.
1956, Ike republican vs stevenson dem, the dem won 56.5% to 40%.
1956 United States presidential election in Alabama - Wikipedia
1960, Kennedy won over Nixon, 56.4% to 42%.
1964 Goldwater the republican won over the Dem, 69.4% vs 56.4%
1968 WALLACE won the state with 65.9% vs, 19.7% for the dem, and 14% for Nixon.
1972 Nixon won it with 72.4% vs 25.5% for the dem.
1976 CARTER won it, with 55.5% vs 42.6%.
So, Jim Crow South, the dems allied with the racists of the South, had a solid hold on 60% vs about 40% of the vote for Republicans.
Goldwater vs Johnson, in 64, it seems at least 30% crossed party lines.
68 looks like an odd outlier, with Wallace taking a huge majority, vs what we can assume were hard core dem and republican partisans of less than 20% for the dem and less than 15% for Nixon. Interestingly, this is AFTER you libs claim the Southern Strategy was in operation...
in 72, Nixon won Alabama, 72% vs 25% for a very liberal North Eastern Dem.
in 1976, again well after the Southern Strategy was supposed to be in operation, Jimmy CARTER, a strong Civil Rights Dem, won the State with a strong, 55 percent of the vote against 42, percent for Ford.
Elections in Alabama - Wikipedia
This is interesting. It shows Carter in 76, LOSING the white vote, 48% to 52%.
The narrative that the Myth of the Southern Strategy tells, is that the Evul Racist Whites of the South, betrayed by the dems, and pandered to by Evul Whites like Goldwater and Nixon, stopped voting dem and started voting republicans.
What we see instead is that 40 percent of whites in Alabama, one of the deepest and most reactionary states, were always voting republican, and that even after all the changes, that number only climbed, at most ten or twenty percent, depending on the candidates.
Ronald REAGAN, only beat Jimmy freaking CARTER, by less than TWO percentage points, in 1980.
Decades of supposed "Southern Strategy", moved the republican vote from 42% in 1962 to 48.7% in 1980.
A shift of less than ten percent of the vote.