Savage,
In regards to your engine size, the 235 (with full oil pressure)has four screws around the base that holds the valve cover down, the 216 has two acorn type nuts on the top of the valve cover that hold it down. The 235 has a sidecover that ends right below the spark plugs and the 216 has a side cover that goes up higher, with holes in it for the sparkplugs. There should also be a flat spot by the distributor that has a serial number on it.
You can also use this link
http://www.inliners.org/ (go to the "castings #" link on the left, and with your engine number you can find out what it is. This link will give you some information on your truck by entering the truck's VIN number.
http://www.americanclassic.com/paint_test.asp 
Samantha
