A thought on Bava Batra 63. It is Ravya bar Kisi. In the gemara, he appears like this:
אָמַר רָבִינָא בַּר קִיסִי, תָּא שְׁמַע: דְּתַנְיָא, הָאוֹמֵר: ״תְּנוּ חֵלֶק לִפְלוֹנִי בְּבוֹר״ – סוֹמְכוֹס אוֹמֵר: אֵין פָּחוֹת מֵרְבִיעַ. ״לְחָבִית״ – אֵין פָּחוֹת מִשְּׁמִינִית. ״לִקְדֵרָה״ – אֵין פָּחוֹת מִשְּׁנֵים עָשָׂר. ״לְטָפִיחַ״ – אֵין פָּחוֹת מִשִּׁשָּׁה עָשָׂר.
Ravina bar Kisi said: Come and hear a proof concerning the halakha in this case, as it is taught in a baraita: With regard to one who says: Give so-and-so a portion of my cistern for his water needs, Sumakhos says: He must give him not less than one-quarter of the water in the cistern. If he qualifies his words and says: Give so-and-so a portion of my cistern’s water for his barrel, he must give him not less than one-eighth of the water. If he says: Give him a portion for his pot, he must give him not less than one-twelfth of the water. And if he says: Give him for his cup, he must give him not less than one-sixteenth of the water. In any event, this baraita indicates that the unqualified phrase: Give so-and-so a portion, should be understood to mean: Give him one-quarter.
Rav Aharon Hyman, in Toledot Tannaim vaAmoraim, writes:
ביומא מב: פליגי במשקל לשון של פרה אדומה ר"ש בן חלפתא ורבנן וא"ל ר' ירמיה מדיפתי לרבינא לא בפרה פליגי אלא בשעיר המשתלח, וההוא יומא נח נפשיה דרביא בר קיסי ואנחו בה סימנא רביא בר קיסי מכפר כשעיר המשתלח, ופירש"י וההוא יומא דאיפלגי בה נח רביא בר קיסי, ומשמע מדבריו שקאי על ר"ש בן חלפתא, ולפי פשוטו קאי ארבינא שמת בימיו, וכן הוא דעת היוחסין וז"ל אמר רבינא אמר לי ר' ירמיה מדיפתא (בגמרא איתא הלשון א"ל ר' ירמיה מדיפתי לרבינא אבל בדק"ס הגרסא כביוחסין ובזה סרה תלונת משכיל לאיתן) טעם בשעיר המשתלח ונתנו סימן רביא בר קיסי מכפר שמת אז.
So we have Yoma 42a (the text above is an error), Chullin 20b, and our sugya in Bava Batra where this Amora appears. In Yoma, it appears as Ravya. In Chullin it is Ravin bar Kisi. In our sugya it is Ravina bar Kisi.
Thus, in Yoma, we have:
אֲמַר לֵיהּ רַבִּי יִרְמְיָה מִדִּיפְתִּי לְרָבִינָא: לָא בְּפָרָה פְּלִיגִי, אֶלָּא בְּשָׂעִיר הַמִּשְׁתַּלֵּחַ פְּלִיגִי. וְהָהוּא יוֹמָא נָח נַפְשֵׁיהּ דְּרַבְיָא בַּר קִיסִי, וְאַנְּחוּ בַּהּ סִימָנָא: רַבְיָא [בַּר] קִיסִי מְכַפֵּר כְּשָׂעִיר הַמִּשְׁתַּלֵּחַ.
Rabbi Yirmeya of Difti said to Ravina: It is not with regard to the strip of the red heifer that they disagree; rather, it is with regard to the strip of the scapegoat that they disagree. And on that very day that they disputed this issue, Ravya bar Kisi died, and they made a mnemonic out of it, associating the halakha with his name: The death of Ravya bar Kisi atones like the scapegoat, since the death of the righteous person atones for his generation.
This helps us place him in terms of scholastic generation. He may have been older at this point. But Rav (not Rabbi) Yirmeyah of Difti was a fifth- and sixth-generation Amora. He was a student of Rava, but also of Rav Pappa and and Rav Pappi, and a teacher of (some) Ravina. I am unsure if the Ravina in this section is Ravina I or II.
In Chullin 20b,
אמר רבינא אמר לי רבין בר קיסי הא דתני רמי בר יחזקאל אין עיקור סימנין בעוף לא אמרן אלא במליקה אבל בשחיטה יש עיקור והא"ר ירמיה אמר שמואל כל הכשר בשחיטה כנגדו בעורף כשר במליקה הא פסול פסול ההוא פליגא
Ravina said: Ravin bar Kisi said to me: With regard to that which Rami bar Yeḥezkel teaches, i.e., that there is no disqualification for ripping simanim in a bird, we say it only with regard to pinching, but with regard to slaughter, there is disqualification for ripping simanim. The Gemara objects: But doesn’t Rabbi Yirmeya say that Shmuel says: Any place that is valid for slaughter on the throat is correspondingly valid for pinching on the nape, but that which is not valid for slaughter is not valid for pinching. The Gemara explains: That halakha disagrees with this statement of Shmuel.
Presumably we are dealing with Ravina II, his student. That may also inform about the other sugya.
Now, I don’t know if Rav Hyman is suggesting these “ben Kisi”s are the same person. But I would suggest it, and that we should not rely on printed text. Ravya is not a common name, which makes it ripe for scribal error, and consider that Ravina appears in context of some of these, which increases the likelihood of an errant copy.
Looking at Bava Batra, Ravina bar Kisi appears in printings.
Also, Oxford 369, but abbreviated, and Vatican 115b:
But other manuscripts have a different text. Florence 8-9 and Hamburg 165 have Ravya, which is correct. Munich 95 likely also has Ravya, but abbreviates it after the yud, which may have led subsequent scribes to expand to Ravina.
Escorial has Ravya. Paris 1337 has Rabba bar Kisi, but that is a clear error.
This is then lectio difficilior. Ravya seems strange to a scribe, thus difficult, while Ravina is easier. And we know from elsewhere that actually, Ravya is a valid name to write. So we should favor it.
Moving on to Yoma, we have lots and lots of Ravyas. Thus:
But there are a few without. Thus, Oxford 366 has Rabba bar Kisi, echoing the Paris 1337 of the Bava Batra sugya:
and Enlau omits the entire segment.
As for Chullin, it is all over the place. While the Vilna printing has Ravina bar Kisi, Soncino has Ravya bar Kisi. Venice has Ravi’ bar Kisi which is probably a shorthand.
And the others either have Ravina bar Kisi, Rava bar Kisi, or Rami bar Kisi. But, see Ravina in close proximity, Rami is close proximity (ditnei Rami bar Yechezkel), and Rava as a frequent name.
At the end of the day, it is Ravya bar Kisi.