Paint Quantity Question

I am really close to being able to start painting the exterior of my 71 Dart project. I have done some test panels, as much to see if I like the color as to get some surfaces covered conveniently. My question is . . . . how much paint do I need to get in order to make sure I have plenty to finish the job? As recap for what I have done/intend to do
- Interior is done
- Underside of car is done
- Vinyl roof to be installed so I don't plan to paint the roof above the trim line (surfaces have been stripped and epoxy applied)
- Need to paint jams, inside of hood and trunk lid, inside of engine compartment, inside of fenders, outside of engine compartment, outside of valence panels, outside of all exterior body panels
- I am using a single stage paint that mixes 8:1:1 with hardener and reducer, so there is not a lot of final product volume gain through mixing.
- I want to apply at least 3 coats to make sure there is plenty to cut and buff.

Anything that I am overlooking? Thanks! L8r

Jim