I would do a bit more detective work before I got to deep into the project. I would try and figure out why the truck was parked in the field, where the tires bad? brakes bad? not running good? A truck that sits in the elements for 8 years can develop many issues. I'd drain the oil while I watched for any contaminants in it. I'd also drain the cooling system and see if it is also contaminated. I would take the gas tank out and remove the sending unit and look inside, see if its full of rust or mud or both, then decide on how to make it useable. Then pull the spark plugs and put a shot glass or two into each cylinder. Then pull the valve cover and get an squirt can and get plenty of oil onto the valve stems. Then you can either use the crank or a pry bar on the flywheel and turn it over a good many turns. Then after letting it sit some oil it up again, then have someone help you and watch the rockers and see that the valves are moving up and down correctly. Once its turning over good and is all oiled up get a battery hooked up and have good connections. Do a compression test and see if the numbers indicate if its got issues or if you have enough compression to get it to run. If things inside the valve cover look like its got lots of sludge and crap built up you may want to pull the oil pan and clean the oil pump screen before you try and fire it up so you don't starve the bearings.
Now you have it turning over and are somewhat sure you have enough compression to make it run you can then work on making sure it has spark to the spark plugs. Once I had good spark I would find a long piece of fuel hose and connect it to the input side of the fuel pump and the other end into a gas can with fresh gas in it. I'd crank the motor some with the ignition key off to get cash into the carburetor. Watch to make sure the float doesn't stick and fill the crankcase with gas or flood over the top of the carb. If you get gas to the carb and don't see any leaks and have spark you should be able to turn the key on and it should fire up.
Any engine needs a few things to run, Compression, Spark and Fuel. If you have these then its just a matter of working out the details.
Don