Getting a little Babbit metal in the sludge layer in the oil pan on a 216 isn't always a disaster. Unlike replaceable bearings, the rod bearing clearance can be tightened up by removing a later or two of the shim pack without doing a full rebuild. Back in the dark ages when these engines were in daily drivers, dropping the oil pan and adjusting the bearing clearance was a routine procedure. The Babbit metal in original equipment rods is MUCH harder than what's used in reconditioned rods, and the OEM rods tend to last a very long time as long as the oil clearance gets corrected regularly. 216 main bearings also have shims, but those can be replaced if they get worn badly. The big problem with swapping main bearings with the engine is in the vehicle is the fact that the crankshaft must be lowered about 1/2" or so for the bearing locating dowels in the upper bearings to clear the counterbore in the block.
Jerry
