Graf's handles the Prvi 6.5X50 brass. I recently bought 200 cases. Seems like it runs about $40 per 100.
I've also used the .35 Remington like Al, but instead of using the Carcano die, I first resized in a .308 Winchester die. Other than that, I did exactly what Al recommeded. So far I haven't had to trim one of the cases since they are a bit shorter than the Jap.
Sam