Will you add some more details like tanks and ladders and stuff?
Also, I just searched for lots of images, and I think your reference might be bad, probably a little too stylized. Most of those I found had the driver's seat thing like this.
Now, I did see a couple that looked like yours, but I think the common image of a cement mixer truck looks more like what I posted.
EDIT: I know, I should've said something earlier.
Well it's up to you, I'd love to use it either way.