Frames were actually orig painted w/ a 90% gloss black enamel, not mirror-black shiny. A typical rattle can gloss black enamel comes out about 90% gloss, decent results can be had on a budget in your driveway. Its popular nowadays to do a black basecoat/clearcoat, the clears are rock-hard urethane enamel. Surface prep makes the difference between a good, bad and mediocre paint job. Powder coat can leave problems, like serial number stamped on frame getting obscured (not good on certain collectable bikes). It also looks like plastic and is too thick; details get lost.
Tip-of-the-month for all you frame restorers: Try rubbing down your dirty, filthy, scratched, dull orig frame paint w/ PENETROL, available at hardware and paint stores. You will be pleasantly suprised at the results in 10 minutes. Its MAGIC