Picked up a three digit 27th like yours at a Pittsburgh, PA show back in the late 80s? It was $50 and I learned at the show before to pay full price if you wanted something. Fellow had a late 99 with the b'net for $50. I offered $45 and eventually got up to $49.99, he wouldn't come down one cent and I wouldn't go up, so I walked away like a dummy.
But back to my story. I had a late 37 that was completely different and that is what prompted me to research the changes in 99s and led to the first 99 book, "The Type 99 Arisaka Short Rifle." Articles on most series were published in Banzai and these were incorporated into the book.