I choose to stamp the main caps on the side, with a corresponding number nearby on the block to prevent getting the cap installed in the right location, but backwards. On the stovebolt engine, all the main bearing bores are different diameters, so it's virtually impossible to get one wrong front to back, but a couple of them can be turned 180 degrees out of position. Since the caps and blocks are machined straight (line bored) on the assembly line, they must be reinstalled in exactly the position they had before. Main caps are not interchangeable from one block to another without re-doing the line bore.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!