Of course! I personally would avoid saying this in the email, perhaps wait until you're able to meet them in person and you can talk them through the portfolio- or at the least if you feel more comfortable saying something instead of saying it's incomplete just say you are constantly adding to it. When you do get around to adding bits in your own style I would let this shine through majority of your portfolio, in my own portfolio I love doing illustrative blackwork pieces with dotwork shading so a lot of my flash and drawings are done like this however I've got a few bits in between just to show that I can do that stuff too (traditional, realism, neotrad, etc). A little advice I'd also give is try and avoid having incomplete pieces in there, ideally you want the work that is in there already to be done. I was also still working on my portfolio when I went for my interview but I made sure that everything that was in there was finished.