1MM is almost .040", which is a huge amount of clearance. You probably have a badly worn crankshaft as well. You will need to measure all the connecting rod journals on the crankshaft and compare them to a service manual to see if the crank is standard diameter, or if it has been reground. All 216 rods have the bearing material bonded to the rod, so the complete rod has to be changed, or they need to be bored out for replaceable bearings.

You definitely need to find someone who is very experienced at working on a Babbit-rod engine to check it out- - -your local shade tree mechanic isn't going to have a clue how to do it!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!