The thermocouple pictured above is the larger, slower reacting "SS White" thermocouple. I prefer the smaller and quicker reacting VDO thermocouple. I have used both with the VDO pyrometer gauge. I switched to the VDO thermocouple when I switched the location to pre-turbine - the SS White thermocouple was too long to fit inside the exhaust manifold or turbine housing.Make sure you make a secure electrical connection from thermocouple to pyrometer wiring. I also recommend wrapping the connections with electrical tape or do something to keep oil from getting on it (which makes the gauge read "0".)
Just noticed that you mentioned you had an Autometer pyrometer setup. I don't have experience with that brand of thermocouple, but I can tell you that the "SS White" thermocouple is larger (in length and diameter of the probe tip) and corresondingly much slower reacting than a VDO thermocouple. I recommend the VDO because of this. The VDO is about 2" in length, the SS White about 3". Good luck and have fun!
Tap the manifold and screw it in or do you tap the manifold and screw in an insert that it slides into? What thread does it use? I'm about to buy one, any suggestions on where to buy? Part #s?