Rice and risotto

I have been trying to get carnaroli rice but locally I cannot, do I have to make any alteration to recipes to use normal riotto rice. I note that on the oven baked risotto carbonara which I want to try you give the amounts in fl ox and mls what is the reason for this as rice is dried and I thought would be in oz or gms or am I show my age and not up to date with things.

On another note I love the delia's Very Fruity Irish Tea Cake my husband favourite but I have also change it sometimes and add 60g of cherries or 100g of apricot apricot and they are lovely additions. I only did it to start with as I had some to use up.