If there is no excessive wear anywhere/the taper is still adequate, and a person can check the lobe taper with a mic/indicator or even just mock it up in a block and confirm the lobe taper isn't gone or less than it should be......sorry if that doesn't make any sense, but it does to me.....there is no reason why a used cam wouldn't work just as well in engine B as it did in engine A.

It isn't just looking for lobes that are gone, it's making sure the lifters will still spin. No spin, no lobe.