both problems were resolved and here were the causes.

the over full fuel gauge turned out to be caused by a new sending unit installed with the gray and black wires reversed in the connector to the harness going forward. apparently too obvious for "deplorable moi" to see right off.

the water temperature was actually more interesting to sort through. even though i confirmed continuity from the sensor connection right through to pin 2 at the back of the cluster there must have been enough incipient resistance as the engine vibrated slightly under running conditions to interrupt this continuity. the chronic offender under the hood was the gray mass connector at the back of the firewall. apparently the yellow wire going in and the yellow coming out were not socializing well at point of meeting inside that connector. after having a talk with them the problem has disappeared.