You could pull more than you could safely stop. I'd stay off the freeways (as you probably already do with the 216/4:11) and keep it small, like a teardrop trailer. Surely you can get your hands on a modern truck for hauling cars...can't you?
There'll be folks who say to upgrade to disc brakes and dual master cylinder and those are fine. But if you have access to a modern truck for heavy work, then keep the '41 stock, dude! Have fun with it, look for some retro stuff to tow, like a varnished wood boat or teardrop trailer, get the stares and live happy!
