If you are removing the AC in its entirety, you'll need the entire non-AC system- crank and water pump pulleys, and alternator mounting brackets & spacers. The AC brackets locate the alternator differently than non-AC setups. I *believe* you can retain your current power steering brackets- but I may be mistaken about that. You may also want to consider replacing the alt. pulley with a single-groove unit, as I believe the diameters are different. Source the pullies as a set, no mixing and matching.
Since 360s never came in '71 Darts, source the 318/340 units. Also be aware that factory AC engines used a different water pump with a different number of impeller vanes, driven at a different speed than non-AC engines, so if cooling issues crop up that may need to be swapped out too.
Your cabin HVAC controls will only be partially functional after the swap, too.
Seriously, it may be cheaper and easier to just have your AC system diagnosed and repaired. I'm sure that in California there'll be days you'll be glad you have it...
