Is the entire inside trunk covered with this speckled paint?

What type of clear coat shgould be used (satin, flat, etc.)

Any other tips on painting the inside of the trunk?

I just finished painting the trunk on my 66 with trunk spatter paint. It takes alot of paint to do the whole thing because it doesn't cover all that well. I would recommend using a primer on the trunk that is the same color as the spatter paint. I had used POR tie coat primer on most of it, and grey Rust Oleum primer on the trunk floor itself. It took alot of spatter paint to cover the light blue primer. It also stays wet for quite awhile: a couple of days in some areas.

Now I need to clear coat, and I, too, would like to know - glossy or satin? I had bought the trunk paint kit from Eastwood and it came with a glossy clearcoat, but I'm not so sure that's correct, or even desireable.

What have other people used - gloss, satin, or flat?

Had the same issues when I did my 69. A good point to remember is use a primer simular in color to the finish coat.
I used satin clear as a top coat. It looks great, took a few days to dry.......

When you say "a lot of paint", how many cans are you talking about?

I'm still not sure about the clear... satin glossy or what?

I think I used about 8 cans for the entire trunk. It's important to use the same color primer - the trunk paint doesn't cover like regular paint. Also, you have to use thin coats, because the paint will "push" the already applied paint out of the way if it's still wet. Now that it's done, it looks fantastic - like a new trunk. But now I don't know whether to use flat or satin clearcoat. I definitely won't use the glossy that came in the Eastwood trunk kit.

It's not a good idea to use primer underneath the splatter paint. The slpatter paint is water based as well. Primer ABSORBS moisture promoting rust to develop. With the slpatter paint being water-based, it's not a good barrier at all for water. In fact, water on a freshly painted (splatter) makes a gooey mess!
Here's what I do for a good looking and long lasting trunk:

Remove all rust mechanically. Sanding; wire brush; grinding; etc.

Apply Eastwood's Rust Encapsulater. I prefer this over POR-15.

Apply a good two coats of Rustoleum GREY paint. This will act as a color base for the splatter paint and help prevent rust.

It will take about 6-8 cans of splatter paint to cover the trunk. Spray them one coat at a time, 24 hours apart and plan on it taking days to dry. A drop light in the trunk will help or let it sit in the sun for a few days. Even a week wouldn't hurt. Make sure the splatter paint is dry!

A clear coat on the splatter paint is a good idea. It's not a factory correct restoration step, but a good idea to make it last and keep clean. Even rattle can clear is OK. It will protect the splatter paint from moisture as well.