I completed the tear down of a salvaged 1957 marine 272 with G heads.  I'm curious if the bulls eye pattern on the tappet surface indicates anything?   Almost all of the tappets had these faint circles, some more than others.  Maybe scratches on first start when new?  Unfortunately, the block's water jacket had cracks on both sides but the internals were all very clean.  The camshaft looks good and is 57 spec with the end stamped Z 201. The G heads found a good home and the rear sump oil pan went to a desperate T-Bird owner.  

Those bullseye marks could indicate cranking or starting the engine with minimal or no lube on the camshaft.   That could have happened from the git go or anytime thereafter.  If an engine sits for a long period of time with pressure on the lifter (valve depressed), then there is some bonding trying to happen between the lifter face and the lifter lobe.  Without adequate zinc being already supplanted on the camshaft when an engine is shut down for a period of time, it very possible to get some increased wear at that point.  Excessive cranking of an engine will also do that.
 
Here is a picture of some high mileage Yblk lifters.

Lorena, Texas (South of Waco)

I guess the million-dollar question is can they be used as-is with the same camshaft.

If the mark(s) were made during dry cranking (extended?) while rotating with little lubricant (and unknown spring pressure), how much damage can they cause to the cam lobe(s) until oil pressure stabilizes and even after that.

____________________________

This 272 engine had been sitting for maybe 35+ years.  I rotated it myself with a wrench on the crankshaft to tear it down.   All of the bearing surfaces on the crankshaft, rods and cam looked pretty good and were wet with oil.  The cam lobes and tappets, of course, were dry since the engine had not been run with any oil pressure for decades.  Maybe the bullseye scoring occurred during tear down.   It was originally installed in a late 1950's Higgins speedboat that only had seasonal use in Colorado.   My thought was it had low hours overall.  The last boat registration was 1987.   The cylinder bores looked good and I could not feel any ridges with my bare finger.   The tappets were all shiny and  fell out readily when I rotated the engine upside down on the engine stand.

If you can feel any grooves or wear with your fingernail, then the lifter is not suitable for reuse.  If it feels smooth and upon checking the tappet face with a straight edge and finding that the center of the lifter face is slightly higher than the outside edge, then it’s a judgment call on your end on whether to reuse the lifters on the same camshaft or not.  My general rule is to always use new lifters on a new camshaft.  If reusing tappets, then best practice is to put the tappets on the same lobes that they were originally riding on.

Lorena, Texas (South of Waco)

Tossed into the metal recycling bin.  Thanks to Ted and all for the thought exercise.