Hello,
As far I as know, there is no PPC accelerator for the A2000. It means it will not be possible to run OS4.0 on a A2000.
Nevertheless, OS3.1, OS3.5 or 3.9 are goos OSs which provide enough power for the 68K applications.
The most powerful accelerators are based on the 68060 (Blizzard 2060, Tekmagic 060 or DKB Wildfire). But your current GVP030/40 board should be ok for the applications you are contemplating.
Concerning your current configuration, if you want to get online with your Amiga, you may need more RAM. There is once in a while some GVP simms on Ebay.
Alma96
