Someone mentioned on a recent speech that the Sh’lah Hakadosh was a reincarnation of Ruth Hamoavia. Can that really be true?

Interestingly we find in Sefer Hadoros (5389) something similar. Not a reincarnation, but rather that the Neshama of Ruth ‘joined’ the Sh’lah when he visited Eretz Yisrael. He provides a Remez of the name of the Sh’lah on the Roshei Tevos (beginning letter) of the eight words of Megilas Ruth that do not start with the letter Vav.