<VV> Crank Main Journal "Turning .010" Question

[MonzaProject]

The crankshaft is a 1966 140 w/PG.

I'm having the main and rod bearing journals turned and need to know what the recommended size should be in the end.

The shop manual says that journals 
#1 & 2 should be 2.0978"-2.0988"
#3 & 4 should be 2.0983"-2.0993"
in STOCK form.

1. Why are they different?
2. What should I have them turned to provided they are in fairly decent shape?
3. What base numbers does a machine shop use on a "worn" crankshaft to calibrate how far to cut when finding the needed distance to achieve a basic .010-.010 turn?

If they cut .010" from the worn crank now they will be "more" than what .010" of a cut would be from stock I would think.  How is this achieved to get proper .010" bearings to fit?

-Monza Project