On the headspace issue, I have seven different Mosins and a set of Okie headspace gages. One day on a lark, I took one bolt and checked the headspace with it in all of them. They all passed.
http://www.gunpartscorp.com/Products/291740.htm Pricey... but if you must, here it is. Try E-Sarco too. http://www.e-sarcoinc.com/mosinnagant.aspx very bottom of the page, half the price of Numrich.