Try some low heat---Then use a 10" pipe wrench on the round edge, that SHOULD work---next is use some liquid wrench--Let it soak a week--Then apply pipe wrench.
could you use a small strap wrench on the knob part, instead of a pipe wrench..at least it wont get all buggered up
I might hacksaw the bolt as close to the carriage head as possible. Then take the knob over to the vise. Use a couple of pieces of wood (curved out) to hold the knob without damaging it. Then use typical techniques to remove the stud from the knob: heat, candle wax (beeswax is best), cut a slot in the end of the stud, grab it with vise grips and if all else fails, drill and ezout. This way you do not mess up the car as it seems to be in pretty nice shape.
Got them off, thanks all. I didn't have a pipe wrench, but I used some channel-locks and didn't chew up the knobs too bad. They appear to be stainless, so I think I can polish out the marks from the tool. Both were right-hand thread, for future searching's sake. Thanks again!
Nah, because I plan to use them again. The top is currently dry-rotted, and the bows need to be refurbished.