Whilst the license of BZ Lead does allow this, it would be helpful if you could clearly distinguish it in the short description so that users don't get confused. It is also helpful to state what you've changed.

Additionally, it is possible to write an add-on mod to the original which simply changes the things that you want changed, rather than copying the entire thing over only to change a few lines.

Sorry I am very new to this, I will look into that. I just added a recipe to have both lead and iron pipes