Air Storage?

How much do I need? I am building a 69 C-10. The previous owner had installed two 380 compressors and two 5 gallon tanks. It took FOREVER for it to fillup!!!!
 
I am wanting to get two 480's and maybe a 7 or 8 gallon tank. Will this be enough air, or is 5 gallons plenty? This will not be a daily driver and I dont plan on being to switch happy!

I have 2 480s on 8.5 gallons on my fullsize chevy. When it is full of air and laid out on the ground, lifting just the front up kicks the compressors on. But I do have enough air on one hit front and back to get to ride height and drive away, so that is nice. I would say get the 8 gallon tank, It doesn't take to long to fill it up enough to get you up and going but is still enough air in the event you do hit a few switches at a stop light. Later,Chad

i have a 480c for sale if you intrested.