If it were mine I would drain all the old gas from the tank, drain the oil. New oil & Filter. Fresh gas. Make sure radiator is full. Pull the plugs give each cylinder a couple squirts of oil. Pull the hot wire to the dist. and spin it over until you get oil pressure. Put everything back together and fire it up. Warm it up a few minutes and shut it off. Check rad. & oil again. Drive ..... if all checks out o.k.

I've also let 'em set a couple years and just charged the battery & fired it up too. Never had any adverse effects either way but the cautious approach is probably better.