Try and get a look at a regular HZ to see what original rivets on an Id plate look like. The chassis number on the Id plate should also match the number on the chassis.
If you find the right van at a bargain price, don't plaster it all over the forums while humming and ha-ing about it. Lots of lurkers around and it could get snavelled from under your nose. If you need any verification send a PM. Byron (hk1837) would be the most knowledgable but most of us regulars will be able to help out in a pinch. Only spread the good news after you've paid for it.