Cassini Maps sounds like what what you are looking for. They offer personalised versions of the various historical OS maps, and the ‘Old Series’ is the one that shows the topography with shading, albeit monochrome, as opposed to the contour lines now used in OS maps. You can see what they look like by entering a location on which the map is to be centred and clicking to see a sample image of that location.
They have resized the original maps to the same scale as Landranger 1:50,000, so you can get both old and new maps centred on the same location in the same scale, and display them side by side (which is what I have done).
Although Cassini offer framed and mounted maps, I would instead get the large format flat option, and get it framed myself.