If the camshaft still had the correct amount of lift on all lobes, the lobe face was still in good shape, and the lifter face was good, theres no problem reinstalling it. When a camshaft or a lifter goes bad, the metal that comes off goes into the oil. It's not big pieces, but millions of very small bits. It will require a complete tear down and bearing replacement if the engine doesn't have a filtration system. I've had two engines I repaired that had bad cams, both were shut down as soon as it started missing. I was able to flush out the metal with solvent without pulling the bottom end apart, the filter had done its job and kept the oil clean. A quick bearing checked showed no signs of damage, so both engines got off with just a cleaning and new cam and lifters.
If the lifters do not have a curved face, they will not last much longer. Sure it might run for a while, but it will quit and you will be right back in to it or looking for replacement.
Yours with all the pitting and worn lifters needs to be replaced or repaired.
Theres no cheap way out of this, any custom machine work is going to cost as much or more than the correct parts, and finding a competent shop to do it in a timely manor is going to be hard. Just finding a shop to do any work is getting hard enough. Just price out brass tubing needed for 12 sleeves and a reamer.
.http://toplineauto.com/wp-content/uploads/2019/04/Lifter-Application-Catalog.pdf These are what I would install.
