I have rebuilt two 216 engines, and Have one in the barn, and I am picking up another tomorrow- They are good engines and will run forever, as long as you keep the lubed up, and do not drive them to hard. With both engines(the first sat unused for 7 years) I used a heat gun to heat the oil pan up to pretty hot, then took out the drain plug, then I pulled them apart from the top down. Bagging and cataloging, lots of pictures are a great idea as you go- I used the 1947-51 truck shop manual exclusively for this work.
I did not pull the pistons all the way out- I loosened the cranks with the engine upside down to look at the bearings. There was no visible damage or excessive wear. The cylinder walls were very clean and there was no noticeable scratches or out of polish areas. I then re tightened the crank- and replaced all the gaskets- Chev's of the 40's has a kit that I use every time that has the graphoil rope rear main seal, and has good quality cork, paper, and bonded gaskets.
They have a kit that does the entire 216 engine.
I went ahead and put in a new thermostat as well for 180'F
the temp rating is a personal preference some run cooler, some run hotter(engines and owners)
I did coat both sides of the head gasket with nickel antisieze(a trick a refinery uses on pump and compressor gaskets to ensure seal, and clean removal for servicing, just keep it away from the edges of the gasket.)
I then button it all up- also wire wheel/brush the exhaust manifold and intake manifold, replace the spring- nickel antisieze the shaft of the heat riser shaft(the manifold heater thing) then put a fresh spring on. I then put then manifolds on- I use assembly lube on every part- the lifters, the push rod ends, everything that moves. I then get it all closed up- and paint it( I use the chev's of the 40's grey color spray paint also- looks good) and paint the whole deal- after wiping down the outside with degreaser- and letting it dry. I paint everything on the engine grey except the fan blades, the crankcase breather, the starter and generator, and distributor- those are black, and my local armature rebuild paints my starters and generators black for me as well as refurbs my manufacturer's tag(delco remy) they come out looking new.
The carb I clean(I use cater W-1) and then oil-bath air cleaner either gets dipped in gasoline/kersoene for cleaning the element(or I replace the element) and the rests gets media blasted, repainted semi gloss black and decal-ed.
It goes quickly because the engines are very basic, and run pretty well.
My 1/2 ton truck has a 216 also, it is original, and except for re-sealing the top end(head and valve cover gasket, side cover gasket, and fresh paint it runs like a champ- cruise at 48mph pretty regularly with my 3 speed column shifter-
I recommend the external oil filter if you don't have one- lots of choices out there- the Fram looks good and just about everyone has decals- or you can find a ac delco unit- orange and blue- Jim carter has the decals for that one- it also looks good.
If you are choosing between the two, I would stick with the 216, and use the money for body work and interior/upholstery. as long as you keep within it operating range it will last a very long time.
Sorry to ramble, but I hope it helps.
