The 460 is famous for exhaust manifolds warping and spitting out bolt caps. Mine did, and I was lucky to be able to do the repairs without replacing a head. The CGVWR rating on my rig is 23,000#, 11,000# on the rear duallies, 7,000# in the front axle, and 5,000# towing. I to a 4,200# Dakota, and use a Falcon2 tow bar and EvenBrake. I also recommend a TPMS to keep track of tire temp/pressure. My old rig has 16" wheels, using LT tires, which are running at the edge of their rating, and several tires have blown on the rear over the last eight years.
Stand by for the "460 Roar"; when the transcooler cuts in, the sound it makes will make you sure the engine is coming apart...but the engine will cool down.
The E4OD transmissionis not the weak point others seem to imply. Have the tranny service, and you should be fine. Just don't expect to run more than 40MPH as you ascend steep grades. On the other hand, take it out of OD and never go down a grade faster than you went up it. Keep track of brake failure run-off ramps, just in case.
One last piece of free advice: check the sway bar bushings. Chances are they need to be replaced. You can only buy replacements on line, as Ford stopped making them years ago.
Hope this helps.