Rings are sized for the cylinder, not for the piston.
From Mercedes Benz you can get, or at least could get, piston in about 0.01 mm increments to fit a given cylinder for repair purposes.
Over size pistons that come in a set of 4 or 5 direct from the manufacturer like Mahle, KS and Nüral are all the same size, and usually machined to fit a Cylinder that is honed to a round number like 91.50mm.
Rarely do you have to hone a cylinder to something like 91.49 or 91.51.
Most of the time the size of the cylinder will be printed on the label of the piston box and the needed clearance is stamped on the piston crown.
The FSM is just a guideline.
I personally would never give one of this pistons less then 0.035mm clearance and normally I give them 0.05mm.

__________________

76 240 D. Bought in 1998 for $25.
85 300D. Got it for free with a bad engine. ( Sold )
60 Unimog 404. What was left of it, was given to me. Now powerd by 617A.
88 560 SEL. Bought without engine and trans. Now powerd by 617A.
67 250 SE. Cuope. For resto or sale.
64 220SE. For resto.