Ben, Too bad about the chop job. Your rifle was made by Toyo Kogyo in Hiroshima. go to this website: http://www.radix.net/~bbrown/japanese_markings.html
It tells what the markings on the left side of receiver mean. I can't qiuite tell which series you have from your picture but it is early or mid war. The series is determined by the small Japanesecharacter in a circle on the far left of the receiver markings. Check also to see if if the bolt numbers match the receiver as well as the dustcover. If its all matching and it has the mum and the dustcover then it is really worth restocking. The stock is toast (too much modification) so you will need to find an original early Toyo Kogyo stock, handguard and lower monopod band. They are distinctive in that they have a reddish finish and will be hard to find (your stock still has some of that red color). Of course just about any original early 99 stock would be better than what you have. Salt Flat