That is not a " Linisher" . " The Linisher" is a trade name for a powerful belt driven sander which has a flat bed and a vertical bed . I own on and it used for removing , forging marks and possible stress risers in the process of lightening and polishing standard forged con rods . I think that is an electric file or point sander ! The best way to balance gudgeon , wrist or
piston pins whatever they are called in your country , is the taper grind the inside end which both lightens and balances the pin at the same time . Simply select the correct size Christmas tree carborundum cone and running inside the end . As you quite rightly say there is very little stress on the ends of the pins and any reduction in reciprocating weight is
highly beneficial considering the forces involved in stopping this mass and rapidly accelerating it in the opposite direction in a fraction of a millisecond. In fact JE will supply this type of pin at minimal extra cost and cut the clip grooves for Spirolox ( flat spring locks) which NEVER come out , even when you want them to ( just joking) ! . As one of the major perhaps
the only importers of JE pistons into the UK during the 90's , the work on these always began with a deburr and removal of sharp edges after JEs machining , possibly adding anti detonation , oil accumulator grooves or extra pin oilers etc before weighing and balancing . Simply polishing those areas and removing stress risers after this work often brought them into tolerance . Good pistons at a price that don't break the bank . Their popularity has been well earned and my walls are decorated with JE decals !