I'm just guessing the steering is power-assisted...car's got fuel injectors. On the other hand, the windows aren't power, they are manual. I don't know about the convertible top...one way to find out is to have one of our Claifornia people go check it out.
This summer I test drove a 1979 Chevy El Camino with a 4 speed manual !!! I must admit it was truly a piece of shit, and like you said, friggin dangerous to everyone, even at 20mph I felt it wasn't my ride. The seller wanted $9.5K. I couldn't even park the damn thing...