For something like you are making just eyeball by volume. It would be hard to mess up a straight Virginia like that one. I find a stoved Virginia that is still in higher case can have quite a bit more weight than a light and fluffy unstoved version and it will take up less volume in the blend.
I always go by weight though, its especially needed for complex blends. But moisture content can make a big difference. With leaf that's very dry or really high case(like perique) it can be up to 30%! Generally it may only make a difference of 10-20%, but this can make quite a difference with more potent leaves like perique or latakia.
Best to have it at a similar case or to do a test on some higher case leaf and weigh it before and after drying to see the difference so you can adjust accordingly. I know for myself that I need to use 20-30% more perique as I keep it stored in high case. My orientals are pretty dry usually so I factor that in a put a bit less when doing a blend.