That's good that you have another opportunity to photograph. I love the way the windscreen wipers and headlights are positioned on each vehicle. They give the vehicles a bit of life I think.... sort of like two old companions...just waiting. That's why I think having them whole would work better. Let us know if you get the opportunity to go there again.
Sorry, can't comment on the B&W conversion...I have never done any myself and am unsure of the finer points in this field.