That’s an interesting topic. Pictures would really be nice. Was it originally a Cleveland car?
Ignoring Italian electrics (and I’m half Italian on Mom’s side), it would probably be best to source an oem sender that matches the gauge. You’ll have to do the “temp conversion” your head, but since boiling water is 100 C, that’s easy. If the senders aren’t available, you’ll need to figure out the “resistance” in ohms and go from there. Italian ohms and American ohms are the same (I think you can thank Marconi for that). There might very well be a problem with a metric sender and SAE threads in the head, I’ve no clue on that.
Do they sell replacement smoke for Farina gauges like they do for Lucas and Smiths?
Tell us more, that’s really cool.