You can, sure. It won't be terribly powerful with the 318 and the 3.73 gears. If its a 727 then you don't have overdrive, so should be fine in 3rd gear.
When I landscaped for a living, the foremens trucks were 3/4 tons, with 318s (fuel injected, though, but only throttle body injection). I towed a smaller trailer, about 2000 lbs, most every day(my carpentry rig)... On occasion, I towed a bobcat on a fairly heavy steel deck construction tilt trailer, probably over 5000 lbs combined load. Not a speed demon, but you can do it.
Plenty have towed with 302s in fords.
I'd think that combo is the max you'd want to run, but it should be able to do it. I'd do a test drive, see how it works. Decide if you need a weight distributing hitch then(it would be automatically recommended for towing a half ton).