How much do you think a 72 coronet with a 318 could tow?

it isn't how much you can tow,

IT IS HOW MUCH YOU CAN STOP!

Use to tow a 19' deck boat with merc I&O with my 70 Duster slant 6 with 3 on floor ...... It pulled it fine ...... WAS I EVER STUPID

9" drum brakes all the way a round and only a class 1 hitch

A lawn mower with 7hp engine can pull a lot. When I bought the 81 Imperial body we put it on a 20' trailer. The guy had a 2 post lift in his building we could not get the crew cab dually in to hook up. This guy hooked on with his lawntractor and started pulling it out, well he flipped the mower over 1st, but the second attemp we were successful in moving it.

Check the tow rating for the car, then remember how old it is.

I would tow an open trailer with a car on it if the car was solid and had the hitch that was rated for the weight being towed