318 variances

I understand that the gas crisis and government regulation was a ***** back in the day but what was so different in the engines from 1971 to 1974 to cause such massive losses? Can an engine from 1974 be tweaked back to the point where it could have respectable numbers like those in 1971 with stock components?
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CID***** YEAR * CompRatio***** Horsepower**** Torque
318***** 1971 * 8.6 to 1 ********** 230 @ 4400 ** 320 @ 2000
318 **** 1972 * 8.6 to 1 ********** 150 @ 4000 ** 260 @ 1600
318***** 1973 * 8.6 to 1 ********** 150 @ 3600 ** 265 @ 2000
318***** 1974 * 8.6 to 1 ********** 150 @ 4000 ** 255 @ 2200
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