I have quite a number of lawyer clients who request big, signature ball nibs on their daily use modern fountain pens, along with some court judges to sign important documents.
These three pens were requested to be modified with BBB 1.50mm ball tips by one of my law minded clients. Modern black Duofold, Modern Lapis Duofold, and a sterling S.T. Dupont.
Enjoy, let me know if I can do the same for you!