You don't really have a graphics card, but the GVP IV24 is a nice video card, similar to the NewTek Video Toaster, but you need the "break-out" box for it to get all the video inputs and outputs to do much of anything with it. Did you get that box?
If it is the correct (and rare) AGA version of the IV24 for the A4000, then it should work as a nice scandoubler/flicker fixer for you. You should be able to find the software for it on the Internet, at least I have seen the version for the A2000/A3000 IV24's there.
Sounds like a nice score, I bet you got that A4000 with all those cards for a low price.