The available chip ram won't be increased if you add a graphic card, the effect of the graphic card is that most of the graphics will be stored in the gfx card local ram and not in the chip memory, I wouldn't increase the amount of chip ram because as redrumloa has said if you use some patches the OS will use the gfx card local ram for almost everything. What you should do insted is try to increase the quantity of ram in your accelerator board, do not use Zorro ram cards, they use 16bit ram and will slow down your system a lot. I guess your accelerator will use ZIP chips or something difficult to find, but if you have a graphic card it would be a good idea to add more 32bit fast ram. If you use picasso96 and you want to see how much gfx card ram you have free search availP96, If I remember correctly there are also some patches that allow you to use the gfx card ram as fast ram, with only 2mb of fast that would help you to run some apps...
@Quixote:
In addition to the 8mb memory zone there is an additional space of about 384kbs for the zorro cards configuration, that's the cause an A2000 still can use the scsi chip of a controller even if it has 8mb fitted, and sometimes even more cards if they don't require ram. A gfx card usually needs some 16bit space free to work.