Can't think of a worse matchup for Hector who I have alot of regard for. Camacho had tremendous ability. Uncommon speed and snap on his punches. Macho didn't throw combination he threw Bees. 5s and 6s in your face. Hector said " I'm a legend. I know I'm a legend because when I walk down the street people come up to me and ask me...Hey Mach! When are you fighting again?!" What more evidence do you need? Homicide is still illegal as far as I know. Armstrong has all the qualities needed to offset what Hector brings. You can't get away from a force of nature like Armstrong. Camacho I'm sure will land alot and may look good early. He was Fast with a capital F. It won't last. Armstrong by TKO 12th or 13th. I can see a quitting on the stool scenario.
It would probably look a lot like the fight Camacho had with Chavez - a one sided methodical beat down.
I like the Chavez reference above, that's similar to how it goes, except Armstrong throws a lot more punches at a faster rate, and non stop aggression that Camacho can't deal with, he back peddles and runs until he either quits from having enough or gets TKO or KOed.