your engine block is CAST
your heads are CAST
your intake manifold is CAST
a 1971 340's crankshaft is FORGED

CAST parts have dates on them indicating when they are CAST (not machined, not assembled)
your engine assembly will have an assembly date STAMPED on it below the driver side head. also, is your car's engine stamped GW340 (orange engine) or GM340 (corporate blue engine)?