Re: not "outside admission"

Stated as simply as possible the eccentric could remain in the same position on the axle if the rocker arms which were "indirect" for the outside admission valves are changed to "direct motion" rockers.
The rocker arm is indirect if the valve stem moves backward when the link block moves forward.
The rocker arm is direct if the valve stem moves forward when the link block moves forward.
The eccentric position can also be kept in the original position if position of the reach rod on the "Johnson bar" is changed from above the fulcrum to below the fulcrum.
I know this sounds confusing with out drawings or diagrams to look at. There is a good discussion of this in the International Correspondence Schools (ICS) instructional manual on Stephenson Valve Gear published in 1937. The serial # for that manual is 1968.
As regards the K-27s I have not seen drawings of the valve gear arrangement for piston valves and stephenson gear. They may well have changed the eccentric position since they probably got new main axles when the rebuild occurred.
I hope this helps answer the question.