Update. As Peggy (SWMBO) said, if you hear different stories from two different doctors, then consider them both.
Read Ron's Injector rebuild article, very helpful, and spoke with a Marine engine mechanic & two guys at the Kubota dealership.
Outcome: Don't mess around! If the Delivery Valve Holder is moved (rotated) then get the Injector pump retuned (rebuilt)
Apparently, moving the DVH in any direction will upset the timing. Which is pretty much what Ron says in his article.
Solution: New Injector pump is $580, but as Ron points out, there is a possibility that the 'New' pump may not fit the 'Old' engine, So rebuilding the pump is the more reliable process.
Notes: If you have to remove the Injector delivery tubes - DO NOT ALLOW THE DELIVERY VALVE HOLDER to rotate! Do what you have to to prevent it moving. The Marine mechanic suggested wedging them in pairs to prevent rotation.
Good news: Rebuilding the Injector Pump & Tuning all three delivery devices to consistent fuel flow is only $350. (Of course, had I been able to leave the delivery tubes in place and just bend them out of the way in order to replace the injectors, then I'd be $350 better off (ok, $350 plus what ever gaskets are needed to replace the injector pump and the air manifold.)
Having a decent Kubota dealer nearby is a huge value and having reliable diesel mechanics within 30 mins of the boat is another. Having folks, like Ron, on this site is huge!
Thanks. Will report progress.
Paul