I think it depends on a few things.
Do you have the original inside box and controls?
IF so the under hood kit is the way to go.
however I don't think this is a great deal.
It is very complete however.
If you are able to piece together parts yourself, and get hoses made, it might be cheaper with one of the other well known kit makers like classic auto air or vintage air for just the underhood parts ordered separately.
you may have to call about the mount to the engine.
condensor for 150, compressor for 250, I am not sure all those odds and ends equal another 400 bucks. but could be wrong.