Almost three years later, I did The Number of the Beast.
A different balance indeed on this album. Way more vocals. Do not also forget to check the first post of this topic for the total overview (the first three albums and their songs).
I actually never noticed this thread and I'd really like to commend your effort - it looks very interesting and I hope you'll keep doing this (I'm just waiting til you get to the albums I actually care about). Good luck!