The southern strategy is real but it's also overstated as being the only reason the south shifted to the Republicans.
Much of the southern shift to the GOP was a product of urbanization-suburbaniztion in the south and the ideological alignment in which conservatives shifted into one party and liberals shifted into the other. The rise of the New South and a southern middle class was a strong part of the shifting of the south into the Republican column.
In 1960 Nixon won Kentucky, Virginia, Tennessee, Oklahoma, and Florida (which was still more southern than not at the time) and got 48.52% of the vote in Texas, 47.89% of North Carolina, 47.27% of West Virginia, 42.16% of Alabama, etc.
In 1956 Eisenhower won Louisiana, Texas, Florida, Tennessee, Kentucky, West Virginia, Virginia, Oklahoma, and Maryland. In 1952, Eisenhower won Virginia, Maryland, Tennessee, Texas, and Florida.
But, Nixon did try to to appeal to southern conservatives with law and order rhetoric and opposition to busing - but most of what he did also appealed to northern ethnics.