generally the engine shouldn't go over 180F ,or 82C..So if you get a thermistor it should be in the 212F or 100C range..
As for a part number unless you know what type of meter your using it could be a 101-104 or a temp sensor LM335/LM35 or a DS18B20
there's no point getting a sender unit or making one unless you know what and how the sender interface's with the meter.
And if your measuring cylinder temp at the exhaust manifold you need a pyrometer..a little different 400-800deg C