I generally have 50g rice, and between 60 - 75g pasta, depending on what I am having it with.
So for example - carbonara, where its just a bit of bacon and some mushrooms etc - I would have 75g pasta, where as a spag bol, id rather have more of the bol - so reduce down the pasta to 60g!
You of course wouldnt have to do that, just my personal preference.
HTH