I did both color options on my slant with a brush. Both were with 1Shot paint. I mixed in some japan dry and some thinner, used a 1" purdy for most of the large surface area, a sword for some smaller stuff, and some throw-away "artist" brushes when I had to cut a line around a part. Both times the paint came out perfect. It also held up to heat and oil. It does nicely in gasoline too- had some gas spill eat away some spray on engine enamel, but it did not effect the 1shot at all. The first mix I did L.Purple mixed with some background White, and the 2nd time after I scraped the block and cleaned it again, I painted it with a mixture of Process Blue mixed with some Ultra White (makes an electrical looking blue). The quarts of 1shot are expensive but worth it, and are intended for sign painting and pinstriping mostly.
The 1shot also held up on the intake; exhaust manifold it melts right off though. I painted the engine bay initially with Rustoleum Hammered Aluminum ($14/quart) and you can't thin that stuff, and it's near impossible to clean out of a brush so I used cheap brushes on that. After that design, when I changed the motor blue, I painted the engine bay Rustoleum Hammered Copper. Both have held up to oil and gas so far if it touches it, and are easy to clean. I am thinking of a change though for that.
I did all of this with a selection of brushes, leaving everything in the car, but i did remove the manifolds spark plug wires, etc and valve cover to do the block and head. 2 coats for all. Purple held up a year and would have gone longer if I didn't repaint it. Blue is holding fine as well.
