All of the items you are looking for are appropriate for the make and series. I don't know how much you paid for the rifle, but original parts will not be inexpensive. The Kokura 22 series was made 1942-43. "The Japanese Type 99 Arisakaicon Rifle" is a very good book for info.
Look at the fore-end of the stock. If it originally had a monopod, there should be marks in the stock. Long rifles are usually more expensive as they were the first Type 99's made, and there weren't that many made. Prices on short rifles depend on series and maker. The more rare, the more price.

Dean (the other one)
(No, I'm by no means an expert, but I do buy the books on everything I have.)