Tremble before the might of my amazing graph:
I basically very roughly traced the outline of the falling bowling ball to get an idea of the speed/timing of the drop. As you can see it's a very steady rate of acceleration; obviously it's a very literal trace, so I don't know how well it will convert to animation. I can always tweak it a bit and remove frames if need be.
The blue and green balls on the left show the motion of the ball's first bounce. It doesn't go very high - the climb (blue) has a big gap and then they're very cluttered together near the top (seems to hover for a couple of frames). In contrast, the decline (green) is very evenly spaced. There's another, miniscule bounce after that one (hardly moves at all) but I wasn't willing to waste much more time tracing that one...!
It's pretty rough but... hopefully it'll give me a starting point.
It took me far, far longer to do that than I'd hoped. I hate this computer.