When you want to develop a certain body part then look up to specific sports that have developed them. Olympic gymnasts have the biggest biceps in the world, they have biceps bigger than their heads.
How did they get their biceps so big? The answer is weighted stretch, as you see they do a lot of iron cross work that stretches the biceps with the entire weight of their body.
So if you want really big biceps start incorporating weighted stretch... either negative pelican curls on rings, Planches or iron crosses.
If you are not strong enough to do that then start using behind the back cable curls and let the weight stretch your biceps for 5-10 seconds before curling it, even just holding it isometrically works too.
Bruce lee used to do this too, isometric holds in a stretched position.
And science supports this too in the Avian study. They have seen a 300% muscular growth with weighted stretch only, the highest muscular growth ever registered.