Series two just underwent a valve job, came out smoking like a shotgun. Techs measure 140 across all cylinders but the E now smokes under acceleration. They say the rings might be culprit requiring another second engine job, after 6K of engine work! How the FHC have good, even compression with such smoke?

 

Were the inlet valve guide seals replaced as part of this valve job ? Or maybe taken off and not replaced ? Seals are put on these to prevent oil being sucked into the cylinders.

 

If it were the rings, it should have been obvious with the head off. Worn rings will show a clean area, roughly about a half inch (depending on the amount of wear) around the periphery of the piston top, mostly on the thrust side.

 

Sounds like your oil control rings need replacing.
An experienced/honest mechanic/repair facility would have warned you that when you do the valves (AKA, a "valve job"), quite often the improved valves sealing the combustion chamber against the engine's compression causes more blow-by through the compression ring slots, resulting in higher oil consumption!
Unlike your compression rings, the oil control rings will not show symptoms of low compression or cylinder wear. Their function is to seal off combustion gases, aid in the heat transfer to the cylinder wall, and both lubricate and scrape down oil from the cylinder wall.
Because of the Jaguar's use of steel sleeve liners in their I-6's, and the oil control ring's being not as hard as your compression rings, they will tend to wear faster and not seal as well against steel as with the typical U.S. made cast iron V-8 engine blocks.
Also, if your engine has sat without running for a while, and the engine was not thoroughly flushed before running, these rings especially can sludge up, adding an extra layer of gunk to help prevent efficient sealing against the cylinder walls.
This will allow your engine to consume oil like a Wright Cyclone engine in a Douglas AD-1 Skyraider.
Other then having someone re-ring your pistons, you might see about finding someone who knows about the application of a solvent like Ring-Free, which also would involve changing the oil and plugs after the application.