They generally have everything you need for surplus parts, but you have to call them, and they are so early 20th Century in their "systems...."
The order is handwritten and a carbon copy of the invoice (how often do you see THEM anymore?
) is even included in the shipment.
That said, I have dealt with them many times, the guys on the phone know their stuff, shipping is reasonable and quick, and more often than not, when the other guys like Sarco and Numrich are "out of stock,: they'll have it.
Actually, here is the link directly to their Arisaka page: http://www.ssporters.com/parts/JAPM38%2099.htm