As long as there's still some Babbit left, you can keep filing. A strand of hair measures about .0015"-.002", so it's not like you're making a huge change in size, or making the big end of the rod oval by much. The hammering effect of a loosely-fitted rod top-to-bottom is what makes rods fail, not a little bit of out of round at the parting line between the rod and the cap. On reconditioned rods with plenty of Babbit, I like to use Prussian Blue and scrape the bearing to a perfect fit with the crankshaft, then add shims to get the clearance right, but yours are beyond much benefit to doing that procedure. Too bad we're not closer together- - - -I've got a couple of good-condition 216's, and I'd be happy to work with you as a mentor on a full overhaul. If I don't pass some of the tricks of the trade along, they're just going to go away when some of us oldtimers kick the bucket!
Jerry
