[rotorwrench]

There has to be clearance to allow for rotation, lubrication, and to prevent galling of the bearing with heat expansion. Folks that do babbitt work prefer to have a crankshaft in hand to fit the bearings to it. They should be set up with standard shims to allow for future service. There are several tools that can be used to check a bore. A T-gauge will work if you know how to use one but a ball gauge can work better. Snap gauges work well too. An inside mike has to be small enough to fit the bore size but they will also work well.

I would talk to someone who does this stuff for a living and find out how they do it successfully. "Bedding In" can mean different things to different people.