temp sending unit question

[MARIOS68PANEL]

First ,Do temp sending units fail and cause hi temp reading?
my truck has 67? - 72? stock gauges but not original to my 67.
It has a GM crate 350 that was resently installed.
Just when it gets warmed up it peggs the temp gauge.
I didnt believe it was correct but I bought and installed new thermostat same thing, new water pump same thing. And then a cheap tremp gauge at Kragens and its running just under 190 steady.
So I am guessing the sending unit that came with the GM Crate 350 has failed or is incorrect for the old gauges
Any Ideas would be helpful. I would like to use the stock gauges.