harrison's map is the one to have.
however, if you want to look at the usgs topo maps of the area, go
here.
you'll want to search - box on the right - for the "mount whitney" map for the summit area and the "mount langley" map which would include whitney portal.
you can either order them for home delivery ($) or download / save them (no $) in PDF format for later viewing. you can then print all or part.
i like to look at them for their info but use the harrison map in the field.
good luck.