Total newbie but have Air Bag lowering questions.

[Vertical Smile]

My late father left me this truck, it's a '79 C10 with just 52k on the clock....his pride and joy.
It's absolutely mint being it was garaged it's whole life.
Before Lou Gehrig's Disease took my dads life he shared many dreams he wanted to do to it.
One of the many things he wished he could of done was to lower it & put disk brakes on all four corners, as well as a new 350.
I recently bought a new 355 Edelbrock crate motor and TH-350 tranny so that part has been checked off the list. 8)
Here's a pic of it as it sits now.



Next is the brakes and to lower it and I've been thinking of getting really extreme. (Even though it kills me to cut the frame).
I'd like to drop it really low like the truck in this pic.



I have no idea how to go about this but I want to do it right & professional.

What kind of parts and cost am I looking at?
How reputable is Air Ride Technologies?
They have what's called an Chevy C10 73-87 -Street Challenge Kit, it's a hefty $6,890.00 but looks to have everything one would need to lower this truck the right way.
Or is there better alternatives?

Thanks in advance, this should be a fun project.

-Mark