I think that Mr. Tassi was not a flute maker but a flute player at the Paris opera.
However this is largely fantasy with some reasoning.
The reasoning is that the Paris opera played 400 Hz until about 1750 (Bruce Haynes  ).
The original Tassi is about 400 Hz. The Tassi flute is not an early flute, simply because before they did not know how to make all three octaves work so well. If it is between 1740 and 1750, it also can hardly be later; it has to come from a place where they still played low pitch. There were two, Berlin but that was 390 Hz as we know from the Potsdam Quantz that allegedly has been Frederic the Great's Quantz, so Paris Opera.
Then this flute has been made by an excellent flute maker that must have been somebody's apprentice etcetera. But nowhere anything about Tassi (not in Tula Giannini). So I think that Tassi was the owner (the seller would have his name only once, this is four times).
The name Tassi is found in Paris in that time, Louis XIV had a surgeon Tassi and there was some librettist Tassi.
From the cd:
The Tassi is a Jed Wentz favorite. The original is 400 Hz for Jed . I have made a copy for him. The original is in the Utrecht collection as well. I had skipped it, although I know the collection well, because it is 400 Hz and needs to be played a while before it really goes. Then Jed played it for me. He was right. This is a very special instrument. This flute is easy from the d1 (also f3) to the a3 (which can be blown with a whisper!!!). I have developed a 392 version by recalculating the whole instrument. I think that that is better than to try to change the pitch by recalculating only a middle piece. The 392 flute plays as well as the 400. Also for this flute please have a look at the players testimonials!
There is a 415 Hz as well, good for W.F. Bach duet playing.
Conclusion: this should be just right for Rameau and the like, Kate Clark also thought this and is using it for Rameau opera. Fantasy, but not all. IF ANYBODY KNOWS BETTER I WILL BE PLEASED TO REPLACE THIS FANTASY!!!
 Bruce Haynes, Pitch standards in the Baroque and Classical periods. Available from UMI services http://www.umi.com ISBN 0-612-08519-08  Tula Giannini, Great French Flute Makers etc. ISBN 0-9466113-05-X