The Apple Macintosh 8-24 display card (Mac display 670) is one of the better cards for the Mac II series, with full memory it gives 24bit color on 640X480 Apple 13in color monitor and other monitors,  and (I believe) gives higher resolutions on multi-sync monitor. There are a couple of varieties of this card, one has a simm socket to add ram and  another has DIP Sockets to put RAM chips there. Setting the video adapter to 640X480, V-Sync, H-Sync and Composite on should work with the 19" Viewsonic. I'm using a 8-24 display card (the one with RAM Sockets - all of them filled) with a Gateway E700 monitor similar to the 19" Viewsonic and it works great.