Just use Pal Hires and expand the screensize by using the Sys:Prefs\Overscan like Cyberstorm said. You can also try to use the special screenmode DoublePal Hires No Flicker !! This works on a vga monitor without using a scandoubler, and the screen is very stable, does not eat extra Chip Memory and is also VERY fast, certainly compared to the ultraslow Multiscan. And you can also use Overscan to expand the screensize to 723x512 or something like that ...
