Thanks, Stephen. Disabling fullscreen enhancements was a great tip, and worked.
I let my frustration subside, reinstalled my 980ti. It was immediately improved (the input lag was fixed with your tip). Then spent a great deal of time experimenting in nvidia Profile Inspector using the Reiza-suggested settings as a base, and have come up with what I think is a rather beautiful setup that is fast and has no lag, and looks really good (not quite AMD Supersampling perfect, but darn close).
One thing I did, seeing this in other forums, was go ahead and set AMS to run as administrator. This necessitates moving the user profiles from the Documents folder to the Steam AMS folder. It seems to run smoother, and eliminates a strange issue with triples and the latest update that resulted in a corrupt loading screen persisting in the left screen.
Another feature in the vertical sync settings of Inspector that I played with was FastSync. It truly eliminated tearing, imposed no performance penalty, and, unlike vertical sync, resulted in no perceptible input lag.
I'm attaching my nVidia Profile Inspector settings in case anyone wants to try them. I do not claim to understand all the settings, but this combination is really working well on my triple 1920x1200 (16:10) 60hz monitors, i7 2600k clocked at 4.6, and stock 980ti.
This is running everything on max or full, except no shadow blur and opponents are on high (otherwise I get memory errors with mod cars at some tracks).