Hi Steven.
Sorry Sir, I completely missed your post. Old Fiat vans are pretty hard to come by. The 850 Amigo probably would be the best to use if you can find one. Most are camper vans though.
There's only 5 or so Panda Vans in the UK so I doubt you'll find one of those.
If money isn't a problem then look for a 500 Gardinarie van as that would be a bit special.
Unfortunately I don't know anyone selling any of these so it's Ebay or Classic cars for sale I'm afraid.