Cam/Lifters or Piston Pin?
I have a near-worn out 250 like this - the lifters tick, and yet if you go 1/2 turn tighter, the engine will miss - too tight. The lifters are pretty worn, on the really bad ones I have to swap in "new" (ie out of the grab-box) used lifters til I get a decent one. Then, the rocker has to be set so it just barely won't tick or misfire.
But, you said you can move things around and it is always the same cylinder - that makes me wonder if it is a loose piston pin, sounds a lot like a lifter, intermittent - worst when just coasting with no load on the engine - could this be it?
How do the bottoms of the lifter[s] look on the ticking cylinders? Still convex as when new or concave? That would be another hint.
