Shoot, if it's been sitting that long, I'd definitely shoot a little oil into each cylinder. After letting that sit for a day, with the plugs out, I'd try to turn the engine by hand just to make sure everything turns smoothly. You don't say which engine, but I'd expect the crank bolt to be 27mm.
That socket, shorty extension and a breaker bar. Laying on your back, right side of engine, pushing up should be the proper direction. With the plugs out, it should turn pretty easy if not seized.
I'd also consider changing every belt and cooling hose (including the heater hoses) before driving it.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.