Ryan, I towed a 34 Plymouth lately with this. 235/ 3 speed, I didn't use the OD though, haha. The 55 handled perfectly at 60 mph . I only did 50 miles , all back roads, for longer hauls I'd recommend one of those torquey 283s... But if you are not in a hurry.... That shoebox with it's flathead should pull your beautiful trailer just fine...
I can imagine weather might scare an aluminum trailer owner. Hail has got to be your worst nightmare!
Those Airstreams don't catch the side winds as bad as a flat side trailer does and that helps a lot. Experience towing 15 and 16 foot trailers behind my 48 in the 80's showed that even with a light trailer and equalizer/load leveler hitch goes a long way in helping keep things under control especially with a tow rig that isn't all that heavy. Along with being a great road trip it sounds like it turned into an exciting one.
Great inspiration for my trip to the flea market. Acme Manufacturing trailer hitch, Kansas City, MO, 1939:
Glad you made it home without incident. Speaking of pulling vintage trailers with cars of the era, check out the 1953 Lucille Ball and Desi Arnez movie, "The Long Long Trailer". Very interesting snap shot of the day, and to watch that Merc pretty much pulling around a house is pretty impressive!