Are you getting the entire truck? Or just the sheet metal? If its complete, its heavy.
I'd rid it of the bed unless you really want it. Then maybe the outer duals unless you want them. Finding tires for those old wheels is getting tough (and expensive). Same with the motor/trans, unless it has an old Hemi, the flathead 6 itself weighs more then a a modern V8 auto trans (not the OD). Weight wise, once the bed, the drive train, and the outer duals are gone, it probably isn't real heavy, 5,000-6,000lbs. I would be concerned about the length, will the tires on both axles fit on your trailer's flat bed? Understand all the weight is going to be at both ends of your trailer. The rear end of cheap trailers is pretty weak, usually, and if that has a 2 speed rear end, its heavy.
Pic, I lifted this off the trailer with an engine hoist (1,000lbs capacity), but what you see was all I bought. No motor/trans, no rear frame more that about 2 foot behind the cab, no front axle.