Siheyuan: Saving the Documents from the Start and Earning a Transfer to the City

Li Wen transmigrated to the 1960s. By chance, he saved a document the Soviet Union had wanted to destroy, earning himself a job at a steel mill. He also happened to arrive just as Qin Jingru had come to meet a potential match. That's when he realized he had landed in the world of the Birds of a Feather, and moved into No. 95 Nanluoguxiang...

P.S. The early part focuses on everyday life, while the middle and later parts are about helping the nation's technology advance.

(This book isn't grim, but the protagonist won't be pushed around. No severed hands or feet. It's a slow-paced, slice-of-life story with a pocket dimension, and it respects the original work.)