No experience with birds, but I do have two house bunnies
It's great if you get a cat while it is still young to bond with the rabbits, but
at that age kittens are developing their skills through play.
Stalking, chasing, grabbing, wrestling - kittens have tons of energy and their focus is usually on bringing down their "prey". As an only kitten, your cat won't have any littermates to beat up on
, so you'll want some interactive prey-type toys for him to hone those skills on, as opposed to your bunny.
Not to say that a kitten can't learn to be gentle and affectionate with rabbits, most can, but interactions should be closely monitered, with the rabbits having a cat-free place to escape to, and the kitty having a fair amount of extra play time.
I had a litter of foster kittens that got along fabulously with our two bunnies, and two of those kittens still live with us
, I'm definately an advocate of bonding cats and rabbits, I think you will likely have great success.
If you have any more specific questions, I'd be glad to help