What shell are you using? I know in bash you can define your own commands (via alias), for example once i made a custom command i called cdsee and it took a single parameter (a directory) and cd'd to it, then ls -lah immediately. made it very easy to do my work, as i immediately saw the contents of said folder.
It should, likewise, be possible, and even easy, to make a command that would run the unzip command, and then immediately chmod +x.
Unfortunately, how to pull arguments is escaping me at the moment. But the simplest answer would be to use a linux machine for the originating zip-job, or making your custom command/alias execute the chmod automatically.