I have done Babbit rod machining, and with the proper setup it is not terribly expensive. Unfortunately, the conversion bearings are getting scarce, and somewhat expensive. Don't even think about finding .020" undersize- - - -nobody's got them anymore. Standard size bearings are also hard to find, so we're left with .010 or .030 undersize.

Rod bearings for a Massey-Ferguson 165 tractor with a Perkins Diesel engine are almost a perfect match for 216 and 235 splasher rods. They are inexpensive and available in bulk, in standard diameter and several undersizes, but they require a little bit of modification to work with a stovebolt engine such as drilling oil holes in a couple of places and machining a groove in the center of the bearing. I'm in the process of building fixtures to do that type of modification.
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!