They needs lots of care and feeding. So you better LOVE the truck,  love being in the garage a lot, and love tinkering with it just to get it going in the winter. More of a hobby really.

You're a glutton for punishment, good luck

Unless you have unlimited funds, you'll need a well thought out plan if you get serious about buying one.

Search on youtube, there are a lot of videos out there showing what people are doing with those old trucks.

If you get lucky and find one with a solid foundation you can restore it, do a resto-mod or really anything in between.

Ford has a number of brand new high performance crate engines that could be used, modern air conditioning could be installed etc.

You're going to pay a decent price for one of these, especially for one worth doing anything with. Guys like to swap out the old motors with modern V8s, and they're starting to be more collector's items if they're original.

If you're not familiar with them, study up on carburetors and distributors. My '79 Catalina was my first adventure into a car with a carburetor. There was quite a learning curve, but I picked it up with the help of a few guys on here. Doc and Chuck Tobias, especially. I wouldn't plan on daily driving it, unless you're into spending a fortune on gas. I drove my Pontiac most of this past week because my DD was out of commission and put 300 miles on her. She runs like a scalded ape, but that old V8 drank almost $100 in gas.

You will want to watch for any kind of fluid leaks, especially around the oil seals. My Pontiac has an off and on leak from what I believe is the rear main. It goes through about a half quart every 300 miles or so. I'm going to do something with it at some point.

The braking system is also definitely something to pay attention to as well. If they're original, plan on replacing the lines and possibly the master cylinder for peace of mind. They were all original on my Catalina, one line got a pinhole when I changed a wheel cylinder, so I just replaced all of the lines and hoses. Replacing that master cylinder was a nightmare because of bad GM quality control - it took 3 masters before I got one that didnt leak. 

Buy an original service manual once you find your truck. Digital copies are available for cheap on RockAuto. I pull it up on my Surface when I'm working on the Pontiac. Those old engine bays are a tinkerer's dream, working room isn't really a problem.

They are not difficult to work on compared to the electronic junk we have today.  They don't have an OBDII port to get you started in the right direction but when you only have to worry about the sources of air, fuel and spark, they are a pleasure to work on.  Points, plugs, condenser, oil and filter, rebuild the carburetor, mechanical fuel pump on the block;  what could be easier?