Dear David, Chuck, Jim, and mid-60s Buick owners who like to be
cool! 
First I should correct myself. I had forgotten that there are brackets in multiple styles for the Nailhead. Here is the Centerville Garage webpage with some listed:
http://centervilleautorepair.com/alternatorSomething else to be aware of is that the evaporator assembly is quite large and occupies a lot of space under the dash. It is so big that I wasn't able to photograph it very easily. Here is a view through the glove compartment door:
Here is another view from under the dash with the passenger side kick-panel to provide some perspective on the size:
Vintage Air suggests using the space for the passenger side fresh air vent to route the hoses. However, some guys on the Team Chevelle forum figured out another route using the old heater box. Here is the hoses coming out of the evaporator assembly and into the engine bay:
Here is the modified header box:
The hoses are then routed between the inner and outer fender on the passenger side for a less cluttered engine bay.
In my wagon, the condenser is mounted in front the radiator like this:
The dryer is hidden behind the battery which in a Special is on the passenger side:
Here are a few views of the engine bay as completed to give some perspective on how everything is routed. In this front view you can see the heater hoses routed to the engine from the heater box assembly.
There is a control valve just to right of the EFI ECU box. Here is a view from the passenger side showing how the hoses are routed to the compressor:
Just for completeness, here is a view from the other side. As you can see, there simply isn't much visible related to the Vintage Air installation:
This engine is a custom Buick big-block based on the 1968 430, but most of these concepts should apply to the Nailhead.
Let me know if you have any questions!
Cheers, Edouard
