new piston rings vs new liner + piston

[Razip Samian <razip@domain.elided>]

Hi,

My Alfetta '81 suffered  uneven compression, oily cylinders (spark plugs
turned black after 2 days of use). My mechanic advised new rings but he had
end putting in new pistons and liner. The old pistons had a thick layer of
carbon on top but otherwise still looks good. A number of questions come to
mind.

1. Am i duped? Under what conditions do you normally replace pistons?

2. Any advice on running-in of new liners+piston.

Thanks

Razip

Alfetta '81
Alfetta GCL '85 (newly aquired, no motor. will probably fit in a 75 motor)

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