And taking over the party was mostly a matter of driving the race-liberal, fiscally conservative Republicans that had been part of the Republican coalition since its founding into the Democratic party while attracting the racist, military-Keynesians from the Democratic party into the Republicans ... and driven as much by the LBJ administration ramming through the Civil Rights and Great Society programs and establishing the massive Democratic advantage in the black vote as by anything that was done inside the Republican party. A modus videndi was sorted out between big government racists conservatives and anti-New Deal reactionaries on who got what say on what issues, and away they went. Nixon was the bridge figure, not a Movement "Conservative" reactionary in his own right, but plenty unethical enough to rely on dogwhistle racist appeals to break the former Solid South in the Electoral College.
Obviously for the professional party establishment that simply wanted power, an inside track in the Electoral College for candidates with "R" after their name was far more important than the reckless and irresponsible policies that the Movement "Conservative" reactionaries actually wanted to enact. Those who were principled moderate Republicans rather than moderate Republicans because that was the path to electoral victory were likely always a minority, perhaps since the decline of the Garfield wing of the party in the late 1800's if not earlier. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.