My Nagoya Series 7 has the grooved safety, machined cylindrical bolt knob, short ladder (no wing) rear sight, front sight guards (short), metal butt plate, and is marked Type 99. The Mum is ground. There is no mistaking the series mark on it! Unfortunately, the stock was sported so the bands and sling swivels are missing. I believe that Series 7 is NOT last ditch. Didn't Nagoya produce Type 99 rifles up to series 12?
In case you're wondering about some of the things we are talking about, Jan 42, check this link which is for a Type 99 data sheet:
http://www.gunboards.com/sites/banza...a.htm#Model_99