All new motors make metal during break in, which is normal as parts wear in
I run all the new the motor I build for 20 to 30 minutes to break in all the flat tappet cam motors I build and then drain the oil and cut the oil filter apart to see how much debris is in the pleats of the filter.
I do this several more times, at 500, 1000 and the 2000 miles after breaking them in to ensure that the oil filter cleans up all together after 1000 miles or third oil and filter change
On your deal if your checking the side play with the motor cold I would want .020 or more minimum per pair, .005 + side play when warmed up
Ain't hot rodding fun