I should finish painting mine this week. I'm not a professional painter and have only painted my own vehicles with the last paint job about 10 years ago.
I have good guns although not HVLP. No spraybooth. The garage I paint in is 35'x50' with a 14' ceiling. Dust isn't a problem but paint overspray in the air is. Some paints are dry before the overspray hits the floor. Some aren't and hang in the air a long time even with vent fans running.
While the actual spraying of paint takes some practice, it isn't that difficult. 95% of the paint job is the prep work..body work, priming, sanding, smoothing, filling, etc.
If you have never painted anything, a GT40 probably isn't a good car to start with. It has very few flat panels, very few straight lines. The air intake scoops below the rear window are a real challenge. Painting stripes adds to the complexity.
The cost of paint and the time required to sand off and redo mistakes or things you don't like can dampen your enthusiasm really quickly.
The paint job is one of the first things that people see when they look at the car and makes that "first impression".
With all that said, I would never send my car to someone else to paint. It has been painful getting the paint to look like I want it to look, but I wouldn't have it any other way.
If you do paint yourself, you must have a respirator suitable for painting. The vapors from today's paints are nasty and painting without a booth and good ventilation makes it that much worse.
Eastwood sells many prep products, sanding blocks, paper, filler, glazing putty, etc.
I've used PPG Deltron products with good results in the past. I'm using House of Kolor paint this time. I didn't buy the paint from Eastwood, but they just started handling HOK products. Whatever companies paint you use, you should stick with that company from primer to clear including reducers. Less chance of incompatability, paint lifting, etc. Get the product sheets for the products you're using. They give mixing and spraying instructions and are invaluable.