Transmigrated to the 70s: Saving the Cannon Fodder Boss

[Dual Male Leads + Period Novel + Book Transmigration + Golden Finger + 1V1 Both Pure] Shen Jianan is a college freshman who gets no love from either parent. After an accident, he transmigrates into a dark period novel and becomes a marginal side character in the story. According to the original text, he wouldn't survive past three chapters—he was meant to be pushed off a cliff by the male lead—a beast in human skin—and die. The purpose was to frame the second male lead Gu Yu, send him to prison, and make the white lotus female lead give up on him. How could Shen Jianan possibly stand for this? He doesn't even indulge his own parents, let alone a scumbag who threatens his life! The young man rolls up his sleeves and shouts, "Just watch how this young master turns the tables and becomes the boss!" What? I have to follow the original plot? If I don't, the novel world will collapse? Shen Jianan declared, "That's your own business. Either don't interfere with what I do, or send me back to my original world. If you can't do that, then shut up. This young master doesn't spoil anyone. At worst, we all die together; anyway, I have nothing to lose and everything to gain!"