360 hydraulic lifter failure

Hey Uncle Bob, so's you know, depending on the heads, lifters can be fished outta their bores, and carefully pulled thru the opening in the head, using a magnet.
Sometimes you gotta loosen a manifold bolt a coupla turns, as it protrudes into the opening.
Easy with fresh engines/lifters, a little more challenging on older engines with deposits.
I've done it a few times, cleaned/changed one or whole sets with the intake on.

I'd clean it, if it's noisy, fish it out and replace it.