A couple of weeks back I had gone thru my photo drawer coming across some old NPZ shots that I was experimenting with. I believe it was printed on Agfa, but everything looked real good and I'm sure I overexposed it by 2/3rd's. Try a roll of the Portra and the new Fuji 800 offering and see how they differ. Try also to keep a diary or a recording on changing the overexposure from a 1/3rd thru a full stop and compare differences shooting one scene. Btw, I think that b&w would do the subject good as well.