The BVision graphics card will only work with a Blizzard PPC A1200 accelerator card. You cannot use it AFAIK on its own. And the PPC card + BVision together cost a lot of money if you can ever find them these days.

The Indivision scan doubler/flicker fixer is a good solution to allow you to run all native Amiga modes on a VGA compatible monitor with no flicker and nice quality visuals. It won't however give you any additional features that a separate graphics card would, such as 24-bit colour, or higher resolutions.

If you want to get as much from your A1200 then you first need to look at converting it into a tower system, and then get a breakout board with some PCI slots. Then you can connect up a PCI graphics card for better graphics. Also a PPC or 68040/60 accelerators need the A1200 in a tower due to the heat they produce.