I don't think any of those fittings posted above will work for you.
The temp sender has a tip on the end that will have to fit through the fitting in the pan, right? All those fittings above are going to have too small of a hole in the center for the sender tip to fit through.
I take it you are trying to do this without having to take the pan off?
I think the only way you will do this is the way that the SC companies like vortech tell you to do to tap the pan for oil drainback, you punch a hole in the side of the pan and then tap it for a 1/2 NPT threaded fitting, then screw a 1/2 npt to 1/4 npt adapter into the hole and put your fitting in there. To keep the metal shavings out of the pan, as much as you can anyway, you load the tap with wheel bearing grease.
The best way of course, would be to pull the pan and have a steel fitting welded in.