The only two ways I know of checking the main bore alignment involves using a long round straight(.0000 run out!) bar that is right at .0005 to .0008 smaller than the I.D. of the main caps torque down to the proper torque specs with the bar inside the main bores, if it turn your golden, if it doesn't turn you may have a problem Verify the I.D. of each main cap to make sure there within the factory specs on I.D. and out of round The other way is to install the main bearings and crankshaft to see if it turns easily with no main seal or run out on the crankshaft Do the basics and let us know what you find The neccessity comes when you suspect a problem, don't fix what ain't broke