Since I saw your other question about trying to identify this engine, is it a Lister or Listeroid? I think all the original Listers have "Dursley England' stamped on them somewhere or cast into the crankcase access hatch. Does it have sleeve bearings or Tapered Roller Bearings? I am not sure about end play for sleeve bearings on an original lister(not sure what they would use for thrust?). If it is a Listeroid with Tapered Roller Bearings, you should have .003-.005" of crankshaft endplay.
Ron