As it has been mentioned, so long as the coolant temp sensors (TempTimeSwitch, FI temp sensor, gauge sender) are in the coolant passages, they could be mounted pretty much anywhere on the head/T-stat housing, even block if needed. There may be slight variations in temps from one spot to another but it won't be enough to make a significant difference on these old design systems. So depending on what parts you find, you can decide where to mount them accordingly.
I'm guessing if the pipe connections on Huss (Looking For Joe) T-stat housing have been tapped for thread in fittings, they will be the US standard "NPT" and not the British pipe thread (they are different). So you will need to get US type fittings or possibly retap them (if there is enough material).
I agree with him, you are better off buying a new O2 sensor, perhaps look online. The TTS on the other hand is quite expensive new so I would try a used one, they are rather durable so a used one should be fine.
There is no "pipe" related to the TTS, if I understood your earlier comment correctly. The sensor threads directly into the head. On one of the pictures from the earlier link, here are the TTS and dash gauge/light senders (left and right respectively), red circle. And a extra boss where another sender was once installed (these heads changed a few times over the years, so there are different arrangements possible), blue circle:
View attachment 16647
All three sensors could be located on these three spots, or any/all of them could be on the T-stat housing. Fiat located them differently at various times. So there really isn't one 'correct' layout.
I'll try to get a pic of a "FI" T-stat housing later today.