The big change in smog laws started in 1972, and also the change from gross HP ratings to net HP flywheel ratings. The "hottest" 440 for '73 had 280 HP @ 4800 RPM, with 380 ft/lbs @ 3200, with 8.2:1 compression. The "hottest" 318 (the 318 was never a performance engine) had 170 HP @ 4000, with 270 ft/lbs @ 2000, and 8.6:1 compression. The new stuff is so much better in every way: more power, better MPG, and cleaner to boot!