69 L78 Framingham Built Chevelle

[sixt9rsx33]

I am going to be restoring the above car, and would like to make sure I tell the painter the correct process to paint the car. Were the underside of the floors a gray primer then the body color overspray shows up on the underside when the rockers are painted? I believe each plats process is different.
What is the correct color of black for under the hood including the cowl area and up to the front windshield.
There is still original spatter in the trunk and the original quarters are still on the car so I will document how they look. Although they will be replaced.

Thanks for the help.

Lawrence