We pulled our trailer...much smaller than the Airstream with out '76 Impala. In 1995 we went across western Canada...over the Rockies and to Vancouver Island. Toured the Island, then went home through Washington, Idaho, Montana and North Dakota, up to Canada. The Impala had the 350 V8 and never burped during the trip.
The big deal is what condition the frame, body powertrain are in. If all is ok, the Caprice would handle it well.
Although two things to consider. Ben indicated that driving far distances with headers can really be hard on the ears. Quite true.
Also as the other poster said...would be wise to check to see how much shipping the Airstream would be. Costs might be comparable.
