Can't you do the thing where you hold down both mouse buttons on boot up and change the output to NTSC from there?
Come to think of it, PAL output on NTSC on my Amiga's always was just part of the screen missing. Usually making it hard to play games with controls on the bottom of the screen. :-) I was in and out of PAL all the time. Even on my A500. Except there, I didn't install a switch to activate the 1MB stuff which included the ability to do PAL, so if I ever wanted to do something that required the 512KB stuff, I had to get out the soldering iron. That one trace on the motherboard pulled up off the board once. I really should have installed a little switch. :-o
