If you're gonna go through that much trouble to paint the engine bay, you might want to consider going the extra mile and hiding all the wiring, and smoothing the bay out (filling holes and smoothing out the seams with Bondo/'glass). I don't think I'll ever have an engine bling-blingy enough to be worth showing off, anyway, so I could care less what the engine bay looks like on my notch, really - as long as it's clean and easy for me to service, that'll work for me.
I didn't know Maaco offered a lifetime warranty on anything. Never figured they had enough faith in their own stuff to put that kind of guarantee on it...
Most hoods are already gel-coated and, for the most part, already prepped for painting when you get them. It's still a good idea to sand it down and such, yourself, but you could still pretty much just drop that sucker off at even a place like Maaco, have 'em squirt it for cheap, and have some good-looking, long-lasting results.