A couple points....

1)
Although nto recommended, PTFE tape usually does not insulate/isolate the threads. It fills the tiny, continuous, gap that forms between the peak and valley of the thread.  The flimsy tape typically is not robust enough to withstand the metal-to-metal shear when the body of the threads make contact and are tightened (tapered threads.) THAT SAID, if you want to assure electrical contact and ease of removal, wrap only the very end of the male thread which will "dam up" the leak passageway, and use some copper content NeverSeize (auto parts store or online) on the threads for electrical continuity and corrosion/galling prevention.

2)
Oftentimes, maintaining a bond between the T cap and engine block is an issue, and the resistance increases and can appear to be a faulty temp gauge  -- you can remove the cap, clean the bolt threads very well, and reinstall with the copper never seize - which helps maintain continuity, virtually reduce corrosion and galling of the threads, and makes removal very easy later on.

3)
Also, a grounding strap can be used on the sender -- like a solid stainless mini hose clamp, fitted with a ring terminal and a bonding wire to ground.  A strap like this works well
www.ultimategarage.com(link is external)
http://www.ultimategarage.com/shop/images/miniclamps.jpg(link is external)​

(link is external)

4)

The burp airlock can probably also be avoided by bleeding the Tstat cap.  The thermostat has holes in its flange to bypass some flow to prevent hot spots in the block while the coolant warms up before the Tstat opens.  Remove the T cap. drill and tap for a 1/8"-17 NPT thread, and install a petcock.  Then release air while filling with coolant, rev/fill until coolant spews out the petcock.