The GOP has only had a genuine conservative nominee for president in two elections and that was Ronald Reagan in 1980 and 1984 (Goldwater in 1964 was a pro-war, fiscal conservative, but was not a social conservative). Reagan won big in 1980 and after four years of witnessing conservatism in action the country gave him a landslide in 1984.
If you look at elections over the last 40 years, the more liberal the Republican nominee was, the worse he did.
Actually, the demographic trends indicated that the Goldwater mix (cut back on Big Government across the board) is the winning formula for modern times.