Amiga 1200 PAL <--> NTSC

[adolescent]

You don't have to swap anything to get a psuedo NTSC picture.  From the A1200 FAQ:

Q. Is there an internal jumper on the A1200 to set it to default to PAL or
   NTSC video?
A. No, but if you're really motivated, you can rig this up. My thanks to
   Tetsuo Oda, who provided the information that connecting pin 41 of the
   Alice custom chip to ground causes the A1200 to default to NTSC, while
   pulling this pin high (connecting to +5V through a 4.7k resistor) will
   make the default power-up state PAL. I would point out that making a
   modification like this on a surface-mount chip is difficult at best, and
   may end up in an expensive motherboard replacement, or, at worst, a dead
   A1200 with no replacement motherboard available.

[adolescent]

Yes, a scan doubler will allow you to use your PAL (or NTSC) A1200 with a standard VGA monitor.