[Nebster]

Thanks, Gordon, you sound like you know a lot more about this than I do!

It is a little lower down my priority list in the huge backlog of mods for this bus, but I do intend to get started researching options right away.  

I didn't realize I could just buy these standard linearizers and put the output almost straight to a VFD, but it makes sense of course.  Being more of a software guy, I was figuring I'd end up rigging up a little microcontroller from scratch, but your links point to something that will probably be more reliable and simpler.

There is already a thermocouple or thermistor inline somewhere, because I can see the water temperature on a readout above the dash.  And it is distinct from the high temperature sender that shuts down the engine, because I had to remove that broken sender last week and run the genset without it for a while.  (As it happens, something else failed 100 hours later, and I managed to boil all of the water out of the system, but it appears the engine survived...  sigh.  I had to limp 1000 miles home running off inverter, engine alt, and whatever power poles I could find along the way.)

Okay, stand by.  :-)