The cause of the dead cylinder

I went over to see this 73 240Z which had a problem running with any load. The owner had conflicting information on either the #2 or #4 cylinder having no compression, so I started with a compression test. The results (front to back) were 150-0-130-190-175-175. Of course, I decided to check the valvetrain. With the valve cover off, I bumped the engine with a remote starter to check the valve lash on #2. The exhaust met specs. The intake was HUGE. The rocker is loose, so I made a video of that.

I tried to adjust the valve lash, but the lock nut was too tight, and I risked rounding it. I told the owner only to drive the car to put it on a trailer to take to one of three suggested local people to examine further and fix.