Matt,
I went down this path a few years ago and I will try to remember what I learned and what I did.
First word of advice...Get the Mannel book (
http://www.amazon.com/Mustang-Ford-Small-Block-1962-1969/dp/B003SFV9JU) because that has everything you need to know to do it exactly as the assembly line did.
If I remember right, all assembly line AC cars had fan-clutches. The dealer installed kits from Form Ford had a no-clutch 5-blade fan.
Here's the things that must be absolutely correct for it to fit and all the pulleys line up.
* Correct front timing cover
* Correct water pump
* Correct water pump pulley
* Correct PS pump (if equipped)
* Correct PS pump pulley
* Correct PS Pump bracket
* Correct Heads
* Correct AC Compressor (most likely cast iron Tecumseh not aluminum York)
* Correct AC Compressor base bracket
* Correct AC Compressor "hockey-stick" bracket
* Correct tube brace from AC Compressor to Intake Manifold
* Correct AC Clutch
* Correct alternator pulley
* Correct Crankshaft pulley
* Correct Thermactor (if equipped)
* Correct Thermactor brackets (if equipped)
* Correct Thermactor pulley (if equipped)
* Correct Hot-Idle Compesator and hoses
* Correct Idler Pulley and Bracket
* Correct Hardware
* Correct Fan
* Correct Fan Clutch
* Correct Length Fan/Clutch Shaft
* Correct Radiator
* Correct Fan Shroud
* Correct Fan Shroud "Z-Brackets"
There are so many different setups that are possible, that for YOUR car to be correct, the Mannel book is almost required. It has all the applicable dates/part numbers/pictures, etc.
The new freon runs at a higher pressure. It CAN be done with the old compressors but the system was engineered for lower pressure which means it works best with old R-12. I chose to stay with R-12.
Here's a dataplate similar to the one you will be looking for on the compressor but with a date stamp, appropriate for your car. (This one was a 1969)