I used a mixed to match paint from O'Reilys called Omni on my MGB and it looks great, but being an enamel it's really sensitive to gas, etc. Some places can mix lacquer in spray cans, but I haven't tried it. The engine compartment requires the same prep as the outside of the car and you need to sand, solvent wipe, prime, and paint at a minimum. I like to use a sealer coat as well or at least a primer sealer to prevent reaction between the original paint and the new. Another option is to go to a local mom and pop body shop and have them mix some good quality two part paint which will be much more durable and use a Preval sprayer.
Good luck, Rut