[drummin89]

First I would see if the motor is free, can you spin it by hand (don't try turning it over with the starter first). If not remove the spark plugs and put some oil in to free the rings (someone will chime in with their choice of oil to do this, luckily I didn't have to). Once you get it free, I would drain the oil and put some fresh in, probably change the filter. The filters on these, if it is the original engine, were a bypass design, meaning that the oil didn't pass through the filter before going to the engine, but just a little got pulled away and filtered and dump back into the pan, so a filter change probably isn't that important). It might be good (maybe even required) to drop the pan and clean it if it was sitting all those years with oil in it, as its probably sludge now.

Next id remove the cap on the distributor and take a piece of sand paper and run it in between the points. Wouldn't hurt to change the spark plus either if you plan to run the engine a bit before pulling it. A coolant, or at least water change might be a good idea, check all the hoses as well.

For the trans, as I never dealt with one of those before, I would think a fluid change would be good after sitting for so long.

The just throw a fresh battery in and see what happens.
*****A warning on the battery, these trucks were 6volt (at least chevy, gmc had their own changes) and if you throw a 12volt battery in, don't turn on any accessories or lights if you plan to keep or sell them later. Also if you plan to keep or sell the stock gauges, unhook them, especially the fuel gauge. The 12 volt will be alright for the starter, but after a while the starter solenoid and the ignition coil will fail, but there are 12 volt replacements.

If I missed anything or made a mistake, someone will be by to correct or add what they have to say.

Good luck and when you get a chance and have a digital camera handy, take and post some pictures.