Fumicho Driving ( translated from ふみっちょドライビング ) on YouTube has got a nice video for you to watch. The Japanese content creator restored a Suzuki GSX400 Impulse at a professional level, with everything cleaned, replaced, and installed in just one video.
Please prepare an hour of your time (or play the video slightly faster) to get the full experience of this restoration build. With 57 or so minutes of restoration to be done, prepare for an ASMR trip to get this bike from disassembled to revving its inline-four up.