There is no way to remove the peeling paint while "preserving" the original paint... you can carefully sand the peeling paint off, but you are going to end up sanding into the original paint in some places, perhaps in a lot of places, and perhaps down to the metal in other places..... you would basically be preparing it for yet another paint job.
Peeling paint jobs can produce a "patina" look that is kind of cool- does that interest you at all? I have a 51 GMC that was painted with a brush a couple of times many years ago, and it looks pretty cool now, as each layer peels away.
If your plan is to re-paint it, then I would use a dual action disc sander and go over it very carefully.
Do you have any pics?
ps- Another possibility is pressure washing. If its really coming off that easily, then some of it might lift with a pressure washer. But even if it did, you have no idea what it looks like underneath the new paint layer- there could be all kinds of bodywork under there, and not the pristine, original paint that you desire.....
