FFG released a facsimile of the original version of WEG Star Wars a few years back, but I don't know if it's still available. I believe that version was before the proper scale rules were added though – as I recall, they just had vehicle-scale weapons deal triple damage against personal targets, and the only personal-scale weapons that did more than 1D against vehicle-scale targets were things like E-Web heavy blasters (you know, that thing the Storm Troopers assemble to shoot at the Falcon as it departs Mos Eisley) that did 2D.It's a pity that the old WEG Star wars game doesn't seem to be available anywhere, anymore. It was a relatively simple D6 system that included rules for how to handle multiple actions. Damage was scaled based on 'scale' of the weapon. Personal weapons were very unlikely to damage vehicles, whose weapons were unlikely to damage starships. The reverse would make a mess of the smaller scale target. All in all a very fast and relatively easy game to play, if you're used to the greater complexity of something like Pathfinder/D&D3.5e.
Edit: When they did add scale rules however, I believe they made them sort of symmetrical. A starship firing on a person would absolutely splatter them, but they'd have a really hard time hitting them in the first place.