Correct size fan and fan clutch

What is the correct diameter fan for a 1970 Dart Swinger 340 with A/C and the max cooling 945 radiator? I'm getting conflicting information. According to Paul Herds Chrysler Muscle Car parts interchange manual 1968-1974 the correct fan for my application is a 7 blade, 18 1/2" in diameter, and is Chrysler part number 2863216. Looking to confirm this information or find out what the correct fan and fan clutch is. Thanks in advance.