_i pried open the sheetmetal and removed the glass lens from a sealed beam and broke out the bulb in the back_
Not exactly.. This bike's original sealed beam head lamp has a metal reflector. The actual bulb is soldered into the hole in the rear of the reflector.
After removing the lens i used a tiny butane torch to heat the bulb's base. The solder melts and the bulb base can be removed.
Prying back the metal edge holding the front lens deserves some illustration. First off, that trim is stiff and difficult to bend. I was very careful to not touch the glass for fear of chipping it.
I found a small needle nose pliers and cut a thin slot or groove right at the tip of the pliers on one jaw, as close as possible to it's end. Once it gets started with a knife blade or sharp flat screwdriver, this groove in the pliers can grab the edge of the metal trim and , little by little, working my way slowly around the lens, pried it all back a couple millimeters.
Once the metal trim is pried back all the way around, the lens can fall out. Then go to work removing the back bulb, etc.