Heat did it.
I cooked the lower in the bearing carrier thread area and, with an impact wrench on my removal tool, it finally came out. The bad news is that it looks as if the threads on the carrier are torn apart; don't know about the housing yet, I'm going to clean it up first, then take a look.
One lesson is that there's an O-ring sealing the bearing carrier on the outside end, so penetrating oil won't reach the threads. I should have applied the penetrating oil, or other stuff, from the inside.
While the gears, and the roller bearing are rusty, overall orange in color, they might clean up. Replacing all of the rusty bits would be cost-prohibitive, compared to the cost of a used lower unit, and the value of the motor. If I can clean it up and make the lower water-tight and serviceable, if not perfect, I'll be happy.