What to know before adding AC

Let me start by saying I'm the perfect combination of dangerous, I know enough to fix things when they need it, but I really only know cars to the extent of the things I've had to fix.

I'm just about ready to make the plunge and order a ClassicAutoAir perfect fit system to my 73 Dart Custom. I gave the guys there a call and I'm looking at just north of $1600 for the kit shipped.

So here are my questions:
1. What do I need to check before I even think about starting? Will I need to add a fan shroud, etc?

2. I know that I'm going to end up having to spend more than the 1600 on the kit, but aside from charging, and buying a new belt of two, what you you guys think I'll end up having to drop cash on??

Thanks as always.

Oh and this is the kit:
1973 Dodge Dart Air Conditioning System | 73 Dodge Dart AC