GeeVee, if the motor has sat for 8 years, the main bearings, cam bearings and rod bearings are almost guaranteed to be bone dry, and there is no way to get oil to those bearings short of submerging the entire block in oil, or pumping some through it.
You can take a brand new engine, run it for an hour, drain the oil and sit it on a shelf for 8 years. If you don't push some oil through the system before you restart it, you can do more damage to it in the first ten seconds it runs than you would driving it every day for 20 years.
You may be one of the few lucky enough to have gotten a truck with a perfectly good engine that has a lot of life left in it. It would be a shame to spin a main bearing and trash a crankshaft, or something worse, just to hear it run now rather than a little later.
