Someone told me I might have a spun cam bearing/bushing?

I need help understanding the path of the oil psi feed system!

The gauge shows oil psi and only some of the lifters are making noise. At idle a few push rods are sloppy loose. None of them were squirting oil when I checked them. That is how far I have gotten in the troubleshooting and now I am stuck.

Do I have to pull the cam and look for the oil passages to be blocked? I was going to swap lifters out of another motor. I had planned on checking the cam lobes and surfaces.

The motor is in an Astro van and I want to repair it in place. Thanks in advance