402 went with cast-only for '71. 454s had forged cranks through '72, then only manual trans Corvettes got the forged cranks after '72. All tall-deck 366 & 427 truck engines came with forged cranks.350hp might have a forged crank. I know that when cast cranks were first used on big blocks in 1968, they were only used on 325hp engines. I don't know if that was still true in 71/72.