Hy MikeE, Merry Christmas, I use the crankshaft turning test, if all the components were from the same engine with the crankshaft machined and new bearings in place, no rear seal and some assembly lube on the bearings, place the crankshaft in the block and check the ability to spin the crankshaft. If it passes the test you can install the two center main caps ( if we are talking the six cylinder 216 - 261 engine) and do the turning test, if it still passes install the remaining main caps and test for turnability. If it is turnable with all the main caps in place it should be fine. The 216 - 261 engines have a different main bearing diameters each main bearing diameter is different from the others, this makes the line boring job more labourious, also with a gear driven cam setup you can't remove much if any material from the block side of the main bearing bores, that would remove the clearance between the cam and crankshaft gears, hope that helps.
