I can't tell you all that much as I didn't do the gibush. And you likely know this already, but just in case you don't (and nobody else responds), keep in mind that the most important thing is to show you're a team player, that you're ready to work hard and can push yourself, and that you aren't in horrible shape. It sounds like you're keeping yourself in shape, so if you really do your best, you'll do just fine. It's not Sayeret Matkal.
Mahal Nahal March '04 draft